Win2000 programs very slow to load

I've been experiencing a problem for the last few weeks, basically when I try to launch certain programs or processes it takes a very long time for them to start. Programs I run all the time like email, Firefox, etc start up normally, but for example when I try to access task manager, add/remove programs, or install a new program there is a very long delay, basically I will click whatever it is to start, then there's a delay of 20-30 seconds where basically nothing happens, then the program starts and executes normally. There's no strange sounds or other indicators to tell me what the problem is, could be hard drive issues or just windows going bad. I've tried anti-virus, spyware removal, hijack this, it all looks normal.

Basically this problem is more of an aggravation than anything else, but I want to find out what the cause of it is.

Thanks for any help!