See to it that it's in the proper size (128x128, 256x256 or 512x512 respectively). You can also try to upload them as .png. Convert them using GIMP or any other image manipulation program. It should work.
Are you positively certain it is actually a .bmp file? Make sure that "Hide known file extensions" is turned off and check.
K, you might want to try and change .bmp to .jpg
That's what I use in GIMP.
Hm, I can't do that.
.JPG lowers the image quality drastically. I didn't say I can't upload images at all. Since .BMP is the best quality possible, the best next thing is .TIF.
Thanks for the help. Very appritiated. I will just continue using .TIF until this problem is fixed.