[X4U] Error (-900)

[ghost town]

I've seen other posts regarding this on other sites, but none got a decent response.  The problem is, I can't drag anything.  Ever.  I can't drag icons to/from the dock, I can't drag icons on the desktop, in any applications... the only thing I can blame it on is an error (-900), which GraphicConverter gives me whenever I try to drag something.  Anyone have any suggestions?  This is really rendering my computer pretty useless and I need a way to fix it...