I have a Medion Composer 5100 that keeps rebooting itself. Computer specs: Intel Pentium 4 530 CPU 3.0 GHz MB L2 Cache 800 Mhz front side bus 512 MB DDR RAM 160 GB 7200rpm Seagate SATA hard drive 8X Sony DVD +/- RW drive 48x CD-ROM 128 nVIDIA GeForce FX 5300 w/DVI Win XP Home Edition I had a friend bring his computer over for me to take a look at and see if I could fix it. Upon receipt it was noticed that the CPU heatsink/fan assembly was lose and lying on the graphics card. I clean all the old thermal compound off and applied a fresh coat. The computer is now rebooting itself at start up. I read a thread on the possibility of it being faulty memory. I downloaded the Microsoft Memory Diagnostic tool and on the intial run it reboot on test 2 on the first pass. It rebooted and then completed 2 full passes of all 6 tests and then rebooted on test 2 of the third pass. I have been able to get the computer to load and am able to perform simple tasks like opening common programs, accessing the internet etc. I use AVG Antivirus and when I attempted run a computer scan, the computer will reboot about a fifth of the way through the scan. I am trying to figure out if the memory is the problem or if it might be something worse, such as a bad CPU or perhaps the motherboard itself. Any help would be greatly appreciated. If this is the incorrect forum for this issue, please direct me to the correct one. Thank you.