BSoD STOP: 0X0000007E on loading Vista x64

Need your Help.

I installed Catalyst 8.3 for x64 OS everything was fine even the Crossfire Option was already activated when I furst run catalyst, so I supposed it recognized my hardware.

I play some games for a while. But this morning when I started Vista again after loading BSoD =
STOP: 0X0000007E (0XFFFFFFFFC0000005, 0X00000000000000, 0XFFFFFA6001BD7088, 0XFFFFFA6001BD6A60)

After some search it could be for Last Drivers installed (ATI of course) first time I could load Vista in Safe Mode, I did not change anything and on the next restart Vista Loaded Normally, I installed Test Drive Unlimited played few minutes, installed TOCA Race Drive 2, play few minutes and shut down the PC. Just to make sure I started again and after load same BSoD and even in Safe Mode now I get the BSoD.

Any suggestion beside trying to return to last good configuration, but than what?

it may be down to encryption (according to microsoft). There is a kb available to try; read the full article here

You may receive a "Stop 0x0000007E" error message after you enable the BitLocker Drive Encryption feature in Windows Vista

Thks Roy69 for your response but this Microsoft KB does not apply to my case since BitLocker is only available on Vista Ultimate and Enterprise.

Thks anyway