Windows 7 Windows 7057 Upgrade Issue

Hello,
Yesterday I've installed Windows 7057 (RC1), I upgraded it from 7048 with a mounted image. I already managed the problem with notepad starting up on each boot up but the new windows boots up for about 10 minutes and when it finally shows my desktop it keeps causing problems. I can move the mouse but suddenly I can't click on anything, than gadgets load up and system makes another freez althoug a gadget shows Core1: 2% Core2: 3% and RAM: 70% FREE, after some minutes it runs ok but freezes when I start installing/uinstalling. All in all full boot up takes up to 15 minutes :/ Any solution ? Thank you for further replies.
My computer:
Core2Duo E8400, 3,5GHz
EP43-S3L Gigabyte Motherboard
2GB HyperX Kingston CL4 ( Dual channel )
250GB SATA (here is the system installed) & 80GB IDE
GF 9600GT Gigabyte MCC