I am trying to find a way to clear up an OS installation I have which is broken. It happened after EDIT Windows update. Fix found see post #18. I Alt F4d out of a pretty dodgy game (as in dodgy coding). Win7 aero failed to reinitiate on the desktop (Win7 x64 Home Premium) and I had a grey taskbar and there was some kind of critical error which I dismissed and decided to restart to clear up the mess. When I restarted I was greeted with a BSOD bugcheck 50, "page fault in an unpaged area" error code 0x490. So I tried safe mode and last known good configuration and got the same. It finds the boot.ini fine and gets to the swirly wirly things and then goes black, monitor goes to zero input and them I get the BSOD. I managed to get the repair mode working, tried to fixmbr from command prompt on the disk which is broken and it completed successfully but would not boot with same BSOD. Tried chkdsk and it reported OK, ran out of ideas. I have a 2 month old backup on a spare drive which I am using to write this on the same machine so I have access to the broken OS from this one. I tried to use this one to reset the page file to zero on the bad OS disc. No help. My guess is it was a foul up with the video RAM due to interaction between the crappy game software and the AMD driver which has left a record of a bad location somewhere and when it tries to boot it calls that bad location has a BSOD and stops there. full error report from failed repair was unknown bugcheck = Bugcheck50 parameters = FFFFF901C06457D4, 0x0, FFFFF96000012CCA3, 0x5 repair acction : system files integrity check & repair result : failed. ErrorCode = 0x490 time taken = 187888 ms I think those long numbers are dodgy RAM locations and I need a way to clear out the bogus RAM locations for the boot process to go ahead, anyone got any ideas how to do that?