XP hangs at desktop at start-up

My 2-month old PC hangs at XP start-up. The desktop appears, the mouse cursor becomes an egg-timer and I can't click anything for around 30 seconds. Ctrl+alt+delete lets me see the task manager and nothing is happening for that time (99% system idle process), and when the time is up all the services start running one by one and I can click.

I can't pin-point when this problem started happening, whether it always did with just XP or since I installed everything, which obviously hinders me somewhat. Obviously I've run AVG, Spybot and updated XP and this hasn't found or solved anything.

I've got very few programs that run at start-up (although if this happens before the services start I can't see this being a cause).

One interesting thing is that if I don't have my LAN/internet connection plugged in (ethernet connection to router) the hang doesn't occur.

I suspect either there are some issues with the networking on my computer (incompatible drivers?) or that an application/service is attempting to update itself or call home and times out after a while. I've tried disabling Windows Update, but this didn't fix the problem.

Specs are Q6600, 2gb 6400 RAM, 2 x T166 RAID 0, 7900gs, XP SP2.

What steps can I go through to fix this? Is there some way I can log data transfer at startup?

you have infected by parite.b virus. clean it and try again.

check date of original post.