This problem lasts in my PC for 3 years now. I have renewed all hardware components except hardisks and CD reader-writers. The thing is that from time to time (say, twice a day, maybe) the mouse stops at any point and doesn't longer respond to movement or click, the screen freezes and the keyboard gets unresponsive. I have to press the reset button. I see no relationship, it happens at any moment (internet open or not, process intensive or not,.... ) I changed mobo, ram, vga, power supply, keyboard, mouse and added a new disk (keeping the original one) Any suggestion to start investigating? I have no ISP but I have a computer in the next room and it works perfectly after 2 years. thanks thanks santiago

I meant I have no UPS (uninterruptible power supply), not ISP, sorry thanks santiago

"I changed mobo, ram, vga, power supply, keyboard, mouse and added a new disk (keeping the original one)" And you're still experiencing the same problem ? First, I would consider the cpu as a possible cause of your problems. Have you changed the cpu and/or HSF over the last three years ? Also, it's possible that this is a software related issue. Have you reinstalled or ran a repair installation of XP over the last three years ?

yes, I changed cpu and reinstalled os (3 or 4 times) The new CPU came with a new fan.. mmm, previously I changed the original fan (AMD K7 processor) by a new one. Then, some months afterwards, I replaced the whole mobo-cpu-ram. I can't remember if this problem started at the same time that original (AMD K7) replacement. Might be, because with the K7 the system came to a "blue-halt" , and afterwards, it didn't....maybe it froze and I didn't care because it was not so often.... but I really can't remember.... Anyhow, the fan is brand new now (6 months) and the spontaneous UI freezing is there, challenging me.... thanks santiago

"Then, some months afterwards, I replaced the whole mobo-cpu-ram." Did you load the new chipset drivers, etc. for the new motherboard(assuming a different chipset) ? Also, I guess it's possible that your hard drive is defective, since you didn't menyion replacing it. Have you run a check on the hard drive ?

no idea about chipset drivers, i did nothing on that matter. How can I check the hd? thanks santiago

The motherboard should have come with a CD with the chipset drivers and other drivers as well. If you can't find the CD you might have to download the drivers. There are many utilities out there for checking hard drives. You could also go to the hard drive manufacturer's website and download a utility to check the drive. I would load the motherboard drivers first, though, and see if that helps.