xp not booting, no error messages

[fncbdy1]

i have an hp pavilion 854n desktop, i run windows xp media center ed. i did a system restore, it said to restart, i did. it got to the "please wait while windows starts..............." screen and stayed there. after about 15 min i turn it off, turn it back on, and i get a black blank screen, no messages, no nothing. when i reboot it the hp screen comes on and then goes to the windows xp screen, then it goes black. any ides or suggestions would be great thanks.:confused:

[AWS]

Could be a bad stick of ram, overheating problem or video card problem.