BsoD; typical or unique...

I guess there are a lot of these problems, so I am glad I came here. Currently I am running in safe mode with networking because Windows 7 will not start normally. I can select which user account, and then every time, while the account is loading, the system goes into a freeze and the blue screen appears. There is always a stop message and sometimes there is even a driver identified (something.sys). I cannot even reinstall from the Win7 installation disk because the freeze happens during installation setup. Some time ago, I took my PC to get serviced because it would freeze, but with no BSOD, just totally lock up, had to press and hold the power button to restart. They did not specifically identify the problem, and at that time, I upgraded to Win7 from Vista. The freeze problems stopped until a month ago, and I ran checks, scans, virua protections, and uninstalled programs like limewire that allow automatic access to the computer. Then the freezing stopped completely, and for a month or so, no pb, until just a few days ago, the computer froze, blue screen comes up, and that is how things have been since. Every time I try to login normally.
I dont know if any of that history helps. I tried system restore, didnt work. Tried to reinstall, froze. I am going to try the driver verifier program next to see if there are drivers in err, but I think this problem may be more deeply rooted...??? Luckily in safe mode I can back my files up, just in case I need to give this machine flying lessons out my window.
Any ideas? I am not super computer literate, but am capable to follow directions.
Thanks, JP

Just ran a verify scan through the command prompt, the sfc /SCANNOW, and it said all is well and in order.