Invalid Color Depth = Open it in MSPaint (or whatever you use), save as a 256 color bitmap, NOT a 24-bit bitmap. (Change the 'Save as type' dropdown menu right below where you put in the filename)
Umm Backtracking a bit, BlueCube how do you save it has a 256 color bitmap?
and by MSPaint i hope you mean Microsoft Paint cause thats all i have