Uninstall Adobe, delete the "C:\Program Files\Adobe" folder, restart your computer, then try installing Adobe Acrobat Pro.
Adobe has a problem with it's uninstalls. The packaging of their software isn't exactly neat. It's a good install, but if you have 2 adobe products installed, like acrobat and reader, and uninstall Reader, acrobat will no longer work.
Even though acrobat installs reader, an update screws it up. I had this problem when people had Acrobat on their PC. We were uninstalling reader (in which case they didn't have it) but the readre uninstall pulled out acrobat.
Basically, delete the folder after you uninstall, restart, do your install.