Guru,
Try this:
Unistall IMAQ. Then try reinstalling the new version. If that doesn't work then uninstall everything: LabVIEW, the upgrade, IMAQ, etc (in reverse of that order). Then install LV, 602up, and IMAQ 2.5.1. That should fix it.
Of course, you can always contact NI and wait for them to tell you the right way to do it, but I am certain that unistalling and starting over will do the trick.
Good luck