A problem has developed on most (but not all!) of the computers on our
network. When a user goes to Yahoo and tries to attach a file to an email
they are sending, they get a message saying 'Invalid file selected' at the
point where they click the Attach button (that is, after browsing and
selecting a file).

This has happened to several different users, with several different files
(different file types). * It doesn't happen in Firefox, only in ie6*.

I emailed Yahoo customer support about it, but they just said my account was
working fine.

Does anyone have experience of this problem or any pointers as to how to
solve it?

Thanks in advance,

Dani