awful awful problem - can't find a solution

I recently built a computer for a friend at work, nothing too fancy, just for office work/internet etc. Construction and installation all went ok, but now, a few days later, I've run into a problem that I can't figure out for the life of me. When the computer boots up, the taskbar suddenly somehow "freezes". The owner has the taskbar hidden, and it's impossible to get to pop back up. If he then opens programs on the desktop, they open with no problem, but then freeze.

What is weird about the problem, is that everything becomes "solved" as soon as the task manager is opened, or as soon as I press CTRL-ESC to bring up the taskbar. The programs start working, the taskbar begins functioning normally, all the problems disappear. The problems then "reappear" if I get a message from the taskbar, like Security Center telling me that an AV program isn't installed, or something similar. Then CTRL-ESC solves the problem completely again. I'm totally lost here. I've removed pretty much everything from the startup menu, disabled a tonne of services, nothing seems to work. When I uninstalled AVG, I thought I solved the problem, but then as soon as the Security Center gave me that stupid yellow baloon telling me that there was no AV program, the taskbar froze again. I'm begging for help here!

here is the HJT log, I'm totally lost…
Edited by paws
Hjt log removed and uplifted as an attachment
📎HJTlog.txt

Due to the demands of my "client" who needed it right away, I simply reinstalled xp. Seems to be working fine now. Thread can be closed.

Hmm, probably an installation file it choked on during install. Is the CD scratched by any means? Just curious

Glad everthing is working OK…(original HJT log replaced as an attachment) and thread is closed