It is indeed most often a hardware error. But you shouldn't worry too much. Depending on what OS you need, it can be the OS being buggy.
Windows 9x for example does it all the time, you shouldn't worry when it does, it's completely normal.
Windows NT based OSes like NT, 2000, XP, 2003 shouldn't be doing it too often, and when it does, it's most likely to be a misconfiguration (reinstall video drivers etc..?) or a problem with your other hardware like RAM etc. If it only happens like once in a week or so, there's nothing to worry about for you. If it happens every few, then you need to think about getting your system checked...
A Physical Dump, btw, is Windows writing whatever information the kernel (or other - depending on the kind) has in memory to the disk, this information can later be used by professionals at Microsoft to see what's wrong. But don't count on them helping you out, honestly.
Comment/Reply (w/o sign-up)