HP 8710P - wierd things after downgrade

Hi!
I posted earlier about the downgrade process from Vista Business to XP pro.
Everything seemed fine at the begining, but now I'm experiencing wierd things on my system.

First, I thought I uninstall HP Backup software, because it lacks the "burn backup on dvd" option, so I prefer to use BootIt NG to make a partition image for my safety. After uninstalling HP backup software, after a reboot, the C partition was extended on the whole hard-drive. Before the reboot, it was 15GB, after reboot, I guess the partition-table got altered somehow, and extended my C partition to the whole harddrive.
I checked the partition (scandisk, Norton Partition Magic) and everything seemed fine... In the end I got my C partition shortened with Norton Partition Magic, ... I didn't loose anything, 'cause I had unpartitioned space after the C drive, but still...

Second, ... my whole system worked very slow... no high CPU usage, no high HDD usage, nothing... once I needed to stop Zone Alarm (pro-trial), and everything got back to normal... wierd...

Third, i get a BSOD from time to time, I didn't got to change the reboot option for this, to see the error message, but I will... tonight...

Wierd things going on my system... Any ideas? (Especially from Greg )

Thanks in advance for the replies (those will shorten my "debug" time )

 

Since last post I reinstalled XP in a cleaner mode, not finished yet.
I will get back to post the whole process and the results.