Launching programs very slow

For a while now, when I use dial-up to log into my ISP or
my company network, my system takes forever to launch a
program or even to open a folder (can take up to a
minute).
If I log off from wherever I'm logged into the problem
remains and I have to restart windows.

I am using a laptop with xp pro. All windows updates have
been performed.
I have run ad-aware, anti virus software, spybot etc. I
have defraged hard drive and cleaned up the regestry.
Running programs are minimal and I see nothing unusual.

Any help would be appriciated.