Random crashing "sound" with no restart

Hey all.

How about this for a brain picker then? So, running Windows 7 64 bit Home Premium and all seems ok (well, actually have had a few problems such as not being able to install games and stuff but they are different issues).

I'm very new to Win 7 so please appreciate that I am still learning the ropes as I was running XP 32 bit for the last 6 years and that is how old my system is (see specs if it helps).

So, a few days ago I am just doing my normal thing like browsing the web and trying to install games etc and then *bump* computer makes a crashing sound but nothing happens.

What?! Did I just actually hear my system fail and it's still....working??

Really, really strange. It's like I'm waiting for it to BSOD or something like there is a delay but no it just carries on. Thought nothing of it but recently it's done it at least once every time I use it. Basically makes the crashing sound and then you can hear it fire up like it's initiating a standard boot up.

We all know our own machines and we know what a restart or BSOD sounds like and Im 100% certain that is what it is.

Never did that in XP and if it did crash, well it would post blue screen and then you would have to do forced restart. Win 7 by the way was an in place upgrade over Vista 32 bit as my mobo wouldn't accept Win 7 from cold (fresh install). I asked a friend and he said it may be Win 7 "masking" Win Vista or something but that can't be right and there is no evidence of another OS on my partition nor do I have a dual boot config etc.

Drivers all up to date and Bullguard has not detected a virus so I have no idea what would cause that and it's totally new to me. Infact, I didn't even know a computer could do that!

I'm just curious, if anything else as to why it would do that and if anyone has experienced this themselves. I have a funny feeling that this isn't an isolated case nor unique.

Yes, you might say "If it doesn't actually crash, then whats your problem?"

Fair question but if it was you wouldn't you at least wonder why it's doing it and try to pinpoint it. I mean lets face it, no system should do that. Thats called teasing :)

Thanks all.