Computer trouble

So my new (second hand) computer was working just fine, when suddenly, out of the blue (pun intended), I got the "Blue Screen of Death". This happened two days ago. At first my PC didn't want to boot up. Eventually after Sabbath I desperately tried something and eventually got it to boot again. But now it is ever so slow. It will be working perfectly fine, but then, say after every 15 seconds, everything will stall -- no mouse movement, no sound, nothing -- and then again after a couple of seconds it will continue again as if nothing is the matter.

When I open the Task Manager, I cannot identify anything suspicious that is eating up my resources during those moments of zombie-like non-performance.

Is it a virus or other malware? Seriously, I do not know. It is even possible for it to be hardware malfunction. I did travel with the PC by subway and bus, so it is possible that it got a knock on the way and the hard drive or something might have been damaged. But why did it only start acting up days afterwards?

Tomorrow I'll get a boot disk and reinstall a backed-up image of the hard drive just after it was formatted. If it is still showing these symptoms after that then I'll know it is hardware malfunction.

Currently it is not broken to such a degree that I cannot work; it is just broken enough to irritate. I better not get so frustrated that perform percussion maintenance on it, by kicking and punching it into obedience or collapse.

Luckily I still have my office PC...

The picture is from Franklarosa.Com.