aqua, i found this registry tool from another tfp thread recently
http://www.ccleaner.com/
worked like a charm. i would also think about checking to see if you haven't accidentally turned on something like 'sticky keys' or the equivalent...sometimes your keyboard options can fuck up simple things like this. is this only when you do it with the keyboard, or with the mouse too? i would also check any options in your clipboard and make sure it's not been changed somehow.