A customer reported an issue that they were not able to checking *.doc files into the Vault (while *.docx files were working).
If they tried it the checkin didn´t proceed and was freezing.
Also the w3wp.exe on the Server had a CPU usage of 100% and IIS needs to be restarted.
The cause was a file called OFFFILT.DLL in the folder C:\Program Files\Common Files\Microsoft Shared\Filters
We are not sure where the file comes from but after moving/deleting the file the issue was gone