Created attachment 124449 [details]
Test ods file

A colleague of mine reported a frequent Calc crash on saving a specific
ods file. Attached is a cleaned up version of that file, with which the
crash still keep happening.

We have made some analysis and observed a strange regularity: the file is
going to crash on the 4th save attempt. Always.

Some important details:
- the file is reported to be quite old and it was used with many previous
  LibreOffice version. It could be that in the beginning it was in xls97
  format but i'm not sure.
- it happens under Windows (tested with Win7pro and Win10pro), but
  not under Linux (tested under Debian with LO 5.1.2, 32 bit);
- it happens with 5.0.x and 5.1.x (tested with 5.0.3.2, 5.0.5.2, 5.1.0.3,
  5.1.1.3, 5.1.2.2) but not with 4.x (tested with 4.4.3.2);
- it happens the same with 32 and 64 bit versions.
- if the file is converted in fods, the crash still happens.
- if the file is converted in xls, the crash doesn't happen anymore.
- if the file is converted in xls, then again in osd, the crash doesn't
  happen anymore, but only with the attached file; with the original one
  the crash keeps happening.
- seems it happens only on that file: i was not able to reproduce the crash
  on other files or on an empty one.

The following steps are always reproducible for me (Windows and LO5.x):
- open the attached file.
- write "Save1" in G2.
- CTRL+S to save.
- write "Save2" in G3.
- CTRL+S to save.
- write "Save3" in G4.
- CTRL+S to save.
- write "Save4" in G5.
- CTRL+S to save.
- Watch Calc while crashing.

Looks like something inside that file makes Calc go crazy.
In two occasion on one PC i was able two see a modal Windows saying:
"Could not create system", as reported in this bug report:
https://bugs.documentfoundation.org/show_bug.cgi?id=94779
The message didn't stay on the screen but was rapidly closed by Windows,
which then showed the message: "Libreoffice has stopped working".
On that same PC, Windows was more verbose about the error and showed those
informations (description field translated in english by me):
-----------------
  Problem event name:	APPCRASH
  Application name:	soffice.bin
  Application version:	5.0.5.2
  Application imestamp:	56b49618
  Module name with errors:	MSVCR120.dll
  Module version with errors:	12.0.21005.1
  Module with errors timestamp:	524f7ce6
  Exception code:	40000015
  Exception offset:	000a7676
  OS version:	6.1.7601.2.1.0.256.48
  Local setting ID:	1040
  Additional information 1:	42ec
  Additional information 2:	42ecd35d8e8d911a59f833b5aef1ab89
  Additional information 3:	9785
  Additional information 4:	9785a313441ce0af37f57b23279261d9
-----------------

Let me know if you need more informations or you need me to do more tests.