Need more info, what upgrades? Need full system specs. Did it work OK after you did those upgrades? Lockups can be caused by anything from bad RAM, bad or insufficient power supply, bad video card, bad motherboard, pretty much anything. Need more details from you about exactly what you did and what is happening. Is it overclocked? If it is, first thing to do is reset it to defaults. If you changed the video card, did you make sure the power supply is good enough to run it and all power is plugged into it?