Just upgraded to 3.5 from 3.3.
Trying to save modifications in xlsx files with multiple sheets (ca. 10) causes the Calc to freeze (“Not responding”). If Calc shut-down not forced through End Program - the computer freezes forever.
Files are small, about 42 KB.
System: Vista x64
Can you please open a bug report and attach a test document?
Can’t reproduce this on Win7 x64, LO 3.5.4.2. No Vista available for testing…