Web player screen corruption

A Web Player issue that some players have reported, but i have trouble replicating.

A texture drawn by this function in OnGUI script is being corrupted as displayed in linked file

 GUI.DrawTexture (new Rect (0, 0, Screen.width, Screen.height), background);

http://savepic.net/6059524.png

Another texture in the same OnGUI call works just fine, though (speech bubble)

Any help with resolving this (or at least info on what it can be about) would be appreciated

Web player is set up to have 1024x768 resolution