Should I reinstall Melodyne in 64 bit version only?

The failure of the 64bit standalone goes a way to explain why the software is unavailable to 64bit SONAR. What it is going to take to make the 64bit demo work I cannot say.

well thanks guys. I appreciate your help.

Final question...I was looking on Melodyne website and it said If the installation of Melodyne was unintentionally interrupted (which is a possibility) and only succeeded in installing Sonar X3, I should run the Sonar installation program a second time, this time remembering to install Melodyne. Should I uninstall any Melodyne components that have been installed already and then run the installation of Sonar again? 

I re-read the original post. Since you own X3 Producer, there was no need to download anything directly from Celemony. Melodyne is included with X3 Producer and the SONAR installer launches the Melodyne installer as part of the X3 installation process. It does make sense to remove Melodyne and SONAR, clean up the registry and the run the X3 Producer installer again.

Melodyne did not automatically launch when I ran X3 installation. That is why I installed it from their website. I will try cleaning up the registry and run X3 producer installer again. Thanks

Cleaned up regristry, reinstalled 3X and melodyne. Still nothing. No rewire option, no Melodyne integrated. Not a happy camper. 

Have you tried the right-click Run As Administrator option?
 

Did Melodyne install with SONAR this time? Running the installer as administrator may help. It also may need background processes like virus scanners shutdown. It may be a MS redistribution library problem. Is the OS up to date? It may be faster to call Cakewalk Tech support for a resolution.

Also, you did say you did a rescan of the VSTs but I always thought you needed to do a reset too, if there are "broken" ones to fix.