Error: A Cocoa NSImageCacheException was not handled:

It would be best to track down what app owns this window, and remove it from your startup items, etc. The best route to follow, in my opinion, would be to try to look at "windowed processes" first and see if anything stands out. You can also hit "Quit process" when you think you've found it and see if this gets rid of the window. When you find the process responsible, you can take it down and try to see if this is something you've installed that might have an update available, or simply stop it from starting automatically. There may be a few ways it's scheduled to start, but once you find it people may be able to give you a better idea on hunting it down and eliminating it.

-Lee