If I try and open a file from within Powerpoint, the directory names are made up of question marks or squares. The last directory in the list will be written properly but if I open this directory I receive the following message:
An uexpected error occurred: I/O error 6.

Because of this problem I have to open all files from Explorer

I've re-installed Powerpoint and the whole of Office but this hasn't fixed the problem. Does anybody have any ideas. Thanks for all you help, Paula.