Even QuickTime didn't solve the problem.
As to this time I tried:
1. uninstalling and reinstalling both RW and VW
2. Fooling with regedit, as jack instructed.
3. reinstalling QT and then reinstalling VW and RW.
4. Deleting all regedit entries of VW, RE and even Diehl graphsoft, uninstalling both, and reinstalling both.
5. e-mailing tech support and getting the advice: check that your RW installer is pointed to the VectorWorks folder, while installing (It did).
After all of that I'm still in the old situation - RW is not asking for serial.
any suggestions other the favorite WIN universe solution - format?
Thanks
Yoav