ok, 1st unplug your computer cord and check inside and make sure all ram sticks are snug, then if they are..take out the cmos battery, it should be about the size of a nickle. and leave it out for about 5-minutes. this will reset the cmos settings. then put it back in.
after that, look for the jumper next to the cmos battery..there should be three metal prongs with a jumper on it, take the jumper off and move it to the other side. then put the battery back in plug back in the power cord, but don't put your cover on just yet.
boot up the computer normally, it should have a screen saying cmos was reset, when you see that turn off your computer. go back inside and move the jumper back over to it's original postiton.
then boot up computer, but hit the f8 key to bring up the start menu, then go to safe mode if you can.