Would have been nice to know what he did though... I have the same symptoms with a Bold configured with our BES. He no longer can view any attachment of type PDF, XLS, DOC. I tried memory cleanup and the device has auto-reboot every day of the week. This particular device has only 9MB of free space in application memory... I have 17MB on mine (same model). I found a description of a bug fix in the BES 4.1 SP6: SDR 135889. When a BlackBerry device user views an .xls file attachment on the BlackBerry device, the file might not display, and the user might receive an “Incomplete input data error” message. But our BES is at V18.104.22.168
Finally I asked the user to remove the battery and it solved the problem! The BlackBerry OS does not seems to completely clean the memory when this feature is activated. It does not either help to reboot every day.