Hi 10x,
You can put that on the bad luck...
Here are a few tips you might already know but I cannot guess your level of expertise

Latest CW uses .msi file = Windows Intaller. I've seen in previous posts that you need a fair amount of free space on the system drive (>1GB free space), even when installing on another drive.
Also, I would advise to try and close all applications and see if CW starts.
Windows troubles like these are difficult to debug... We could try a Remote Assistance via MSN if you have High Speed internet access...
Cheers,
Alban.