1. Machines are known to crash due to "pre-existing conditions." Look at most of the XP Service Pack failures. Outside of that HP AMD SP3 debacle too many were malware damaged OSes that fail when the service pack was installed.
Same story with security suites. You take a machine with a dinged up OS and install "this" and it no longer boots the OS. This story repeats hundreds of times daily.
2. About your Toshiba. Why not use the recovery medi?. It's not like you didn't backup what you couldn't lose. Or did you?
Several months ago I took the advice of my ISP, Comcast, and Installed Norton security software through the Comcast portal. During installation it asked to remove the McAfee softwaare (the previous free security suite from Comcast). After installation, my Toshiba laptop, A155, Vista Home Premium, cicrca 2007 would not restart. It keeps trying to repair itself. Will not start in safe mode. Only can boot from Knoppix disk. I called Comcast, they immediately dodged the issue. Norton in the Phillipines first sent me to their green incompetent help desk. Then I Waited over 45 minutes for "supervisor" who never came on so I hung up. Right now I am still so angry at Comcast Norton and MS, I could kill. (Vista should have bankrupted MS for the damage it has done and I will NEVER EVER EVER EVER USE OR RECOMMEND NORTON ANYTHING AGAIN.). Can anyone tell me how to turn this Toshiba paperweight back into a computer?