When I turn on the computer I get the usual screen and can even go into the bios and make changes. When it turns over to the hard drive I see the windows is starting and can go to the choices of safe mood after which a screen full of text lines then screen goes black then to blue and it reboots. Any thoughts would be helpfull. By the way it does simular with a knoppix live cd except for the blue screen. twice when cutting it off for a BRIEF sec the full screen linux distro was visable the it cut off. I am baffled so are we, whats the question ?My question is why am I losing the video? I tried ANOTHER video card and another hard drive with no change. ? power supply issues maybeCheck for heat problems as well....clean out the insides with compressed air using a QTip to hold the fan blades in place when blowing them out...
And while the side PANEL is off by all means swap in a KNOWN good PSU of the same or greater wattage to see if that's the problem...
The other possible culprit could be BAD RAM.

Just an afterthought...the card could be going South...we'll cross our collective fingers and hope this is NOT the issue. Thanks for the help. I have cleaned it with canned air and do not feel that is the problem. will change PS next. or swap ram with a known good stick.
Sounds like MBR is corrupted.