1) updated system bios
2) formatted and done a fresh reinstall of windows xp with latest drivers from hp site (including intel chipset drivers).
3) tried various version of drivers on the pci bridge (microsoft and intel), none of which made a difference.
The laptop has the Intel 852/855 GM/GME chipset and the possible faulty pci-bridge is the 82801DBM (ICH4M).
Anything else i can try or is my best guess of faulty chipset correct? Would really like a second opinion before i throw it in the bin