PC is a two year old Dell XPS with Vista Business - all updates current. I use it as a games machine so, although it has an internet connection, its relatively "clean" apart from game software. I do have a Steam account active. I use Systemsuite 9.0 (SS9) for maintenance and anti-virus, but Vista for firewall. PC working normally, PC stops working normally: About ten minutes after last switch on, a couple of SS9 messages flash up to say that "x" was a known threat and was being quarantined. Messages too quick to see the details, but one mentioned a Steam file, and the other appeared to be a normal system file. Almost immediately, I experienced the Vista BSOD for the first time... I cannot now get a stable boot-up. The PC now cycles endlessly through one of about three different scenarios: (1) crashes to BSOD from any one of the "safe modes" selected; (2) randomly shuts down and re-starts from anywhere in the boot sequence, but with no BSOD; or (3) runs through the "start-up" repair sequence, boots up to normal desktop, gets almost stable but then SS9 kicks in, blocks two files, and the whole thing goes tits up again. In case (3), I desperately load task manager and try and race to disable anything that might be causing the crash. I can exit steam and a few other things, but cannot identify the SS9 process. The desktop is functional for about a minute before it crashes - and will not load any selected programmes or settings - hence hard to deactivate SS9 or other start-up programmes. I have tried the recovery disk to repair (ie haven't gone as far as re-install yet), but this just leads to (3) again. BSOD lists the code "0x000000F4". Web searches show that this is a generic code that can cover many different faults, so its not much help. One problem with Vista is that it is very hard to tell when the initial boot-up has finished - my machine thrashes the disk continuously, with no indication what it is doing. I think my "blocked" files just happen to be normal drivers being loaded - rather than a trojan or something hostile - and it is this that is causing the system shutdown. Unfortunately, because I can't achieve "safe mode", I can't interrupt the normal boot process to try and disable the SS9 protection. Any ideas how I can get out of this mess without a complete re-format (balls-ache to repeat all the activations, updates and settings - to say nothing of my game saves...). I'd like to disable start-up programmes like SS9 outside of the boot-up, but can't see a way to do this if safe mode is not working. Thanks for any advice!