Any idea what may be wrong?
GL balked while were copying (or attempting to) texture data to it... unsure why, but I've replaced that not so informative error message with a much nicer one, so if you are on the widget branch, could you pull the latest changes and try again, if just for a more informative error message?
I noticed your MG topic (having the same issue) in the info their error message supplied I did notice the texture dimensions were 750x750... not powers of two... might be an issue with those drivers?
Anyway, try the latest and see what it says, should provide more info, I'm asking through glu what that error number MG reported means, so it should be a little nicer