Lag when starting programs

This isn't specifically about Guild Wars, though it may relate; I've just found that this community is pretty useful for general computer issues as well as those with GW.

In the past few days I've encountered some very strange lag whenever I start programs on my computer. When I start any program, GW, Ventrilo, or Firefox, for example, the computer lags severely for thirty seconds or more before responding again. Even Windows Explorer seems to lag out for minutes at a time. I can't figure out what might cause this, because these programs should, and used to, open in a matter of seconds.

Possible causes?

P.S. It was a sudden issue beginning within a couple days; also, the lag is largest the first time I start the program after the computer being shut down or in sleep mode, after that programs start pretty much normally.

not sure but check if you have extra prog running without you knowing about them

Hm, I don't think so, I looked through the process list and I didn't see anything super-unusual.... I'm looking for more information on some of the apps that I don't recognize, but I'm not sure if that's the problem