Cacheproblem with thumbs in IE

Hi there

Have found a bug, have been searching on the forum but can´t find any topics about this issue anywhere.

The problem is as follows:

Lets say you have a picture called wallpaper.png and rename it to wallpaper1.png, then you upload a new and different image to same folder called wallpaper.png. When its uploaded the thumb wallpaper.png is the same as the old wallpaper.png that now is called wallpaper1.png. Its only the thumbs that are the probs, if you rightclick on the thumb, choose view, then its the right image.

Have also tested it on http://ckfinder.com/demo and its the same problem there, I have tried on different computers also.

Any ideas how to solve this ?

Best regards/ Reino