Unable to “save as” a document

Hi,

A client of mine uses a windows xp prof.desktop and office 2003. He uses a windows 98 as file sharing server. He is able to save a document in word to the server with no problem but whenever he tries to use an existing document and use “save as” he gets an error ” The folder isn’t accessible, folder maybe located in an unavailable location or protected with a password”. The problem seems to occur only on that pc ( i tried it on another desktop; worked fine). I applied the latest patches for office, tried to boot in safe mode with networking…. still has the same problem.
The only thing that i suspect is the microsoft antispyware software.

Any ideas.

Thanks