Cant open attachments in GroupWise 5.1

[Johur]

I am running an NT4/Netware 4.11 network. I have just set up an XP laptop & installed GroupWise 5.1 client on it. Everything works except that the user cannot open any attachments that come in through Groupwise. The GW is only an internal mail source (not connected to external email at all). I've checked by logging him in at another XP station & he can open attachments ok there. Also I've logged myself into his laptop & get the same error. It is "GroupWise - Error: Not enough disk space on drive 'C:' to perform this operation. Delete one or more files to increase disk space." The laptop has 50GB out of 52GB free, & is running with 448MB RAM. I upgraded the Novell client from 4.83 to 4.90 with no different results. I've tried multiple types of attachments (word, excel, .pdf, .txt files) with no luck. Also, I can save the attachments, but only to a network drive, not to the local c: drive. I can also "view" the document using whatever viewer GW uses. I have checked all of the settings I can find in GW against other XP boxes I have working & all are the same. Anyone have any ideas?