Hi guys and Gals - first time at this so please forgive any unintended ignorance. I have quite a lot of computer experience but I have come upon a problem I cannot solve. About 6 months ago a friend came to me with a Compac Presario P4 where the monitor light flickered green and went back to orange when he turned the machine on. I replaced the AGP graphics card and the machine worked for about 3 months and then he had the fault again. This time when I replaced the AGP card it had no effect. Eventually after replacing the motherboard with on board video, battery, CPU, CPU Fan, Power supply, memory, the machine worked again. It seemed to be the CPU that finally made the diference. Then he asked me to install a modem during this process the machine suddenly decided to have exactly the same fault as before. The only original parts are DVD rom, CD Writer, floppy drive and IDE cables. Unfortunately there is no internal speaker but machine starts up all fans run all drive lights come on and hard drives boot up. If I switch montor off the on the light flickers green for about 2 secs then goes back to orange. I have tried disconnecting floppy and Cd/DVD drives but to no avail I have removed and re-installed each component in turn and I have tried resetting the bios. Any more ideas?

Tried a different monitor??

Yes - The monitor also works with other pc's I have