Installed & ran Spyware Doctor, now Windows won't start! Please help

Hi,

I installed Spyware Doctor on my computer, ran a scan for malware, and was asked by the program to reboot ... now Windows won't start up again. The screen with the Windows logo and the moving "progress bar" appears, but instead of loading Windows after a few seconds the screen just turns black and nothing happens. If I push the power button, the same thing happens. Windows just won't start.

I've tried starting Windows in safe mode and with the "last known good configuration" but each time the black screen comes up instead of Windows. I'm a little low on memory (about 1~2 GB left on my hard drive) and Spyware Doctor found a few viruses on my computer (but supposedly fixed them before the reboot attempt) ... would these factors have anything to do with this? I had no problems with my computer before I installed and ran Spyware Doctor, so I have to believe the program's the root of my problems. But now that Windows won't start, I don't know how/if I can uninstall the program.

Please help! I don't know what to do ... many thanks in advance.