It would help to know which O/S the workstation is using.

More than likely there is a dead temp file that needs to be deleted manually. (If memory serves me correctly) In Windows XP look for c:\documents and settings\user_name\Local settings\temp. Delete the contents of this folder. Any file in use cannot be deleted and any file not is use is generally no longer required or will be recreated next time it is required, so this is a fairly safe task.