Numerous audio pops all of a sudden - suggestions?

I've been using Sonar with the same computer setup and hardware for years with no serious problems. All of a sudden yesterday I started getting numerous audio pops. I went ahead and reverted to a previous good image file thinking something got corrupted on my C drive. That didn't help. So that rules out the OS or programs. I then reseated all the plugs and cables and computer cards in my computer and sound card box thinking maybe a loose connection was the culprit. It now appears that this is a hardware failure problem. So what is the most likely culprit? Video card on the blink? Ram, motherboard, sound card, power supply, 28 inch Hanns-G monitor, HD's, (run defrag or scandisk), or what? I have 2 Echo Layla24 sound cards. The pops are intermittant, but sometimes are numerous, other times minutes may pass with no pops. They are very short duration midrange sorts of pops, ones that to me sound like a sound card conflicting with a video card or something. Any suggestions on troubleshooting. I have a few computers to swap parts out of.

What kind of a house are you living in? Do you have clean power? Sometimes such "out-of-nowhere" disturbances can come from a refrigerator (or the neighbours fridge) that is about to break down or fluorescent light tubes that have started to blink (in another apartment or room) etc.

Have you emptied your picture cache recently?

Did anything you installed recently do a firmware update?  Placing an older OS image back on wouldn't replace firmware on a piece of hardware (like audio or video).  If so, you might want to see if you can reload previous firmware on the given device.

Another thought (although not as likely) is an IRQ conflict between your audio/video cards.  You could take a look in device manager and see if that could be happening.  A new IRQ assignment can occur if you've recently added or switched around any hardware device onto your machine.

Hope this helps,
Tom

Thanks everyone for your good suggestions. It could have been one of a number of things. I put a different video card in and all the pops went away, so it was clearly the video card that simply went bad after years of good service. The only other thing I did was to unplug the power of my Hanns-G 28" monitor and then replug it. I suppose it's unlikely that could have caused it.