Error de conversion de epub a mobi

Hola a todos. Normalmente leo bastante del foro ya que me soluciona los problemillas que tengo, pero esta vez me ha surgido algo que no soy capaz de arreglar.
Tengo el libro Diccionario de la lengua española (23ª Edición).epub. No lo he encontrado en mobi con esta edición para tenerlo en el Kidle como diccionario. Lo he intentado transformar en calibre pero me da error. Pongo aquí el log. ¿A alguien le ha pasado esto?¿hago algo mal? Gracias.

calibre, version 3.40.1 (win32, embedded-python: True)
Error de conversión: Fallo: Convertido el libro 1 de 1 (Diccionario de la lengua española (23ª Edición))

Convertido el libro 1 de 1 (Diccionario de la lengua española (23ª Edición))
D:\Calibre Portable\Calibre\app\pylib.zip\dateutil\parser.py: 601: UnicodeWarning: Unicode equal comparison failed to convert both arguments to Unicode - interpreting them as being unequal
Conversion options changed from defaults:
verbose: 2
output_profile: 'kindle_pw'
cover: u'C:\\Users\\ADMINI~1\\AppData\\Local\\Temp\\calib re_u3m5vj\\44oj8q.jpeg'
input_profile: 'kindle'
read_metadata_from_opf: u'C:\\Users\\ADMINI~1\\AppData\\Local\\Temp\\calib re_u3m5vj\\_444h0.opf'
Resolved conversion options
calibre version: 3.40.1
{'asciiize': False,
'author_sort': None,
'authors': None,
'base_font_size': 0.0,
'book_producer': None,
'change_justification': u'original',
'chapter': u"//*[((name()='h1' or name()='h2') and re:test(., '\\s*((chapter|book|section|part)\\s+)|((prolog|pr ologue|epilogue)(\\s+|$))', 'i')) or @class = 'chapter']",
'chapter_mark': u'pagebreak',
'comments': None,
'cover': u'C:\\Users\\ADMINI~1\\AppData\\Local\\Temp\\calib re_u3m5vj\\44oj8q.jpeg',
'debug_pipeline': None,
'dehyphenate': True,
'delete_blank_paragraphs': True,
'disable_font_rescaling': False,
'dont_compress': False,
'duplicate_links_in_toc': False,
'embed_all_fonts': False,
'embed_font_family': None,
'enable_heuristics': False,
'expand_css': False,
'extra_css': None,
'extract_to': None,
'filter_css': u'',
'fix_indents': True,
'font_size_mapping': None,
'format_scene_breaks': True,
'html_unwrap_factor': 0.4,
'input_encoding': None,
'input_profile': <calibre.customize.profiles.KindleInput object at 0x05D5BEF0>,
'insert_blank_line': False,
'insert_blank_line_size': 0.5,
'insert_metadata': False,
'isbn': None,
'italicize_common_cases': True,
'keep_ligatures': False,
'language': None,
'level1_toc': None,
'level2_toc': None,
'level3_toc': None,
'line_height': 0.0,
'linearize_tables': False,
'margin_bottom': 5.0,
'margin_left': 5.0,
'margin_right': 5.0,
'margin_top': 5.0,
'markup_chapter_headings': True,
'max_toc_links': 50,
'minimum_line_height': 120.0,
'mobi_toc_at_start': False,
'no_chapters_in_toc': False,
'no_inline_navbars': False,
'no_inline_toc': False,
'output_profile': <calibre.customize.profiles.KindlePaperWhiteOutp ut object at 0x05D55230>,
'page_breaks_before': u'/',
'prefer_author_sort': False,
'prefer_metadata_cover': False,
'pretty_print': False,
'pubdate': None,
'publisher': None,
'rating': None,
'read_metadata_from_opf': u'C:\\Users\\ADMINI~1\\AppData\\Local\\Temp\\calib re_u3m5vj\\_444h0.opf',
'remove_fake_margins': True,
'remove_first_image': False,
'remove_paragraph_spacing': False,
'remove_paragraph_spacing_indent_size': 1.5,
'renumber_headings': True,
'replace_scene_breaks': u'',
'search_replace': '[]',
'series': None,
'series_index': None,
'share_not_sync': False,
'smarten_punctuation': False,
'sr1_replace': None,
'sr1_search': None,
'sr2_replace': None,
'sr2_search': None,
'sr3_replace': None,
'sr3_search': None,
'start_reading_at': None,
'subset_embedded_fonts': False,
'tags': None,
'timestamp': None,
'title': None,
'title_sort': None,
'toc_filter': None,
'toc_threshold': 6,
'toc_title': None,
'transform_css_rules': '[]',
'unsmarten_punctuation': False,
'unwrap_lines': True,
'use_auto_toc': False,
'verbose': 2}
InputFormatPlugin: EPUB Input running
on C:\Users\ADMINI~1\AppData\Local\Temp\calibre_u3m5v j\k6g5at.epub
Found HTML cover OEBPS/Text/portada.htm
Parsing all content...
Parsing OEBPS/Text/ncl_indice.htm ...
Parsing OEBPS/Text/portadilla.htm ...
Parsing OEBPS/Text/portada.htm ...
Parsing OEBPS/Text/Preambulo_0001_0000.htm ...
Parsing OEBPS/Text/Real_Academia_Espanola_0002_0000.htm ...
Parsing OEBPS/Text/Asociacion_de_Academias_de_la_Lengua_Espanola_0003 _0000.htm ...
Parsing OEBPS/Text/Colaboradores_0004_0000.htm ...
Parsing OEBPS/Text/Agradecimientos_0005_0000.htm ...
Parsing OEBPS/Text/La_vigesimotercera_edicion_del_Diccionario_de_la_R eal_Academia_Espanola_0006_0000.htm ...
Parsing OEBPS/Text/Articulos_de_muestra_0007_0000.htm ...
Parsing OEBPS/Text/Advertencias_0008_0000.htm ...
Parsing OEBPS/Text/Abreviaturas_y_signos_empleados_0009_0000.htm ...
Parsing OEBPS/Text/a_0010_0000.htm ...
Parsing OEBPS/Text/a_0010_0001.htm ...
Parsing OEBPS/Text/a_0010_0002.htm ...
Parsing OEBPS/Text/a_0010_0003.htm ...
Parsing OEBPS/Text/a_0010_0004.htm ...
Parsing OEBPS/Text/b_0011_0000.htm ...
Parsing OEBPS/Text/b_0011_0001.htm ...
Parsing OEBPS/Text/c_0012_0000.htm ...
Parsing OEBPS/Text/c_0012_0001.htm ...
Parsing OEBPS/Text/c_0012_0002.htm ...
Parsing OEBPS/Text/c_0012_0003.htm ...
Parsing OEBPS/Text/Verbos_irregulares_0037_0002.htm ...
Parsing OEBPS/Text/c_0012_0004.htm ...
Parsing OEBPS/Text/Creditos_0038_0000.htm ...
Parsing OEBPS/Text/d_0013_0000.htm ...
Parsing OEBPS/Text/d_0013_0001.htm ...
Parsing OEBPS/Text/e_0014_0000.htm ...
Parsing OEBPS/Text/e_0014_0001.htm ...
Parsing OEBPS/Text/e_0014_0002.htm ...
Parsing OEBPS/Styles/global.css ...
CSS import of missing file u'OPS/css/page-template.xpgt'
CSSImportRule: While processing imported style sheet href=../../OPS/css/page-template.xpgt: IOError(u'Cannot read Stylesheet.',)
CSS import of missing file u'OPS/css/page-template.xpgt'
CSSImportRule: While processing imported style sheet href=../../OPS/css/page-template.xpgt: IOError(u'Cannot read Stylesheet.',)
Cannot get referenced stylesheet u'../../OPS/css/page-template.xpgt', keeping rule
ValueError, unknown url type: OPS/css/page-template.xpgt
CSSImportRule: While processing imported style sheet href=../../OPS/css/page-template.xpgt: IOError(u'Cannot read Stylesheet.',)
Parsing OEBPS/Text/c_0012_0005.htm ...
Parsing OEBPS/Text/g_0016_0000.htm ...
Parsing OEBPS/Text/h_0017_0000.htm ...
Parsing OEBPS/Text/i_0018_0000.htm ...
Parsing OEBPS/Text/j_0019_0000.htm ...
Parsing OEBPS/Text/k_0020_0000.htm ...
Parsing OEBPS/Text/l_0021_0000.htm ...
Parsing OEBPS/Text/m_0022_0000.htm ...
Parsing OEBPS/Text/m_0022_0001.htm ...
Parsing OEBPS/Text/m_0022_0002.htm ...
Parsing OEBPS/Text/n_0023_0000.htm ...
Parsing OEBPS/Text/n_0024_0000.htm ...
Parsing OEBPS/Text/o_0025_0000.htm ...
Parsing OEBPS/Text/p_0026_0000.htm ...
Parsing OEBPS/Text/p_0026_0001.htm ...
Parsing OEBPS/Text/p_0026_0002.htm ...
Parsing OEBPS/Text/p_0026_0003.htm ...
Parsing OEBPS/Text/q_0027_0000.htm ...
Parsing OEBPS/Text/r_0028_0000.htm ...
Parsing OEBPS/Text/r_0028_0001.htm ...
Parsing OEBPS/Text/s_0029_0000.htm ...
Parsing OEBPS/Text/s_0029_0001.htm ...
Parsing OEBPS/Text/t_0030_0000.htm ...
Parsing OEBPS/Text/t_0030_0001.htm ...
Parsing OEBPS/Text/u_0031_0000.htm ...
Parsing OEBPS/Text/v_0032_0000.htm ...
Parsing OEBPS/Text/w_0033_0000.htm ...
Parsing OEBPS/Text/x_0034_0000.htm ...
Parsing OEBPS/Text/y_0035_0000.htm ...
Parsing OEBPS/Text/z_0036_0000.htm ...
Parsing OEBPS/Text/Apendice_0037_0000.htm ...
Parsing OEBPS/Text/Verbos_regulares_0037_0001.htm ...
Parsing OEBPS/Text/f_0015_0000.htm ...
Referenced file u'OPS/css/page-template.xpgt' not found
Reading TOC from NCX...
Merging user specified metadata...
Detecting structure...
Flattening CSS and remapping font sizes...
Source base font size is 14.00000pt
Removing fake margins...
Found 2 items of level: p_3
Found 63 items of level: div_1
Found 28 items of level: div_2
Found 93948 items of level: p_2
Ignoring level p_3
div_1 left margin stats: Counter({u'': 63})
div_1 right margin stats: Counter({u'': 63})
div_2 left margin stats: Counter()
div_2 right margin stats: Counter()
Negative text indent detected at level p_2, ignoring this level
Cleaning up manifest...
Trimming unused files from manifest...
Trimming u'OEBPS/Misc/page-template.xpgt' from manifest
Creating AZW3 Output...
Serializing resources...
Splitting markup on page breaks and flow limits, if any...
Creating KF8 output
Generating KF8 markup...
Python function terminated unexpectedly
(Error Code: 1)
Traceback (most recent call last):
File "site.py", line 101, in main
File "site.py", line 78, in run_entry_point
File "site-packages\calibre\utils\ipc\worker.py", line 199, in main
File "site-packages\calibre\gui2\convert\gui_conversion.py", line 42, in gui_convert_override
File "site-packages\calibre\gui2\convert\gui_conversion.py", line 27, in gui_convert
File "site-packages\calibre\ebooks\conversion\plumber.py", line 1270, in run
File "site-packages\calibre\ebooks\conversion\plugins\mobi_ou tput.py", line 329, in convert
File "site-packages\calibre\ebooks\mobi\writer8\main.py", line 497, in create_kf8_book
File "site-packages\calibre\ebooks\mobi\writer8\main.py", line 65, in __init__
File "site-packages\calibre\ebooks\mobi\writer8\main.py", line 328, in chunk_it_up
File "site-packages\calibre\ebooks\mobi\writer8\skeleton.py", line 191, in __init__
File "site-packages\calibre\ebooks\mobi\writer8\skeleton.py", line 276, in step_into_tag
File "site-packages\calibre\ebooks\mobi\writer8\skeleton.py", line 81, in tostring
MemoryError