I have a powerpoint file (*.ppt) that I often use.

Today, for no logical reason, PowerPoint refuses to open this file.

I get the message : "PowerPoint can't read the outline from P:\test.ppt.
No text converter is installed for this file type".

I have already tried the following:
- convert it to pdf
- change the file name
- change the location
- change the extension to *.pps

nothing helps. Is there anything else I can try?