Let me see if I can describe what happened here.
I transfered my bulletin board from a UNIX to a WIN2K server. The .gif images in UBB6 worked fine when uploaded to the UNIX, but look corrupted when uploaded to the WIN2K server.
I could open the .gifs in Photoshop before upload and they looked fine, however, once uploaded, if I used "right-click" and then "save picture as", then the image would lock-up my Photoshop Software when attempting to opening the file for viewing+.
I opened all images and icons prior to FTP transfer in Photoshop and re-saved them using Photoshop's "Save for Web" function. This corrected to corruption problem when uploading to the WIN2K server.
Although the UBB images and icon .gif's worked fine on the UNIX server, and the problem appears to be WIN2K server related. It is interesting to note that I altered the "saved" dither settings on the UBB .gifs and the problem was corrected. Thus the FIX, is altering images in the software prior to uploading.
I would suggest that you take this information to your developement team and share this experience with them. I believe the WIN2K Server/UBB .gif conflict will become more serious as more hosting servers go to WIN2K servers.
Thanks for your help, and I apologoze for rambling, but I just spent 3 Days working on this problem, and find my solution may be worthy for others to know about. My GOD I was frustrated and the fix was quite simple once the problem was identified.