I just recently reinstalled Windows 7 x64 and was almost back up and running with the exception of waves giving me a hassle. The GUI was black. I saw many threads about this and for me, they were useless. I was on the phone with a support guy and he kept going to the graphics as the cause. Nope! Here is the email I sent him:
 

Hi
 
I was able to figure out the problem. The problem was, as I suspected, that files were in the wrong place. I moved the "waves shell" around and found some things out. The "waves shell" was in the "Program Files\common files\VST2" folder. I removed that and took the "waves shell 64" from the Waves folder in "Program Files (x86)" folder and put that there. I then placed the "waves shell" file in the "Program Files (x86)\common files\VST2 folder. I have not tried the 32bit GUI yet as I only need them in Harrison Mixbus. I will try those tomorrow and send you another email letting you know the results.
 
I do appreciate the time you spent with me and hope that the guys who you were going to talk to can help others with this information. What happened is I tried, initially, to install the plugins to the VST folders in the common files instead of letting it go where the installer wanted to go. I think there is an issue where the installer is putting files in the wrong place or, my install was just a fluke.
 
Have a good one.
Robert
 
I forget the exact name of the waves shell so you would have to look to figure it out.