windows explorer using 50% CPU when idle

Hi, well my problem seems to be very common, but after seaching the www + MS + HP Tech support I STILL AM STUCK.

i am running XP on a HP Laptop, 3gb ram, a few days ago windows started to slow only 10mins after reboot. this has got worse, now it hangs and shows 50% cpu1 useage within 30secs of booting.

i have no viruses, malware or spyware, checked multiple times with different software.

At first the problem only apeared at the office when connected to a LAN network, at home on a wireless network is was fine, but now this too shows HIGH CPU1 USEAGE @50%.

I HAVE Disable fast index, and uninstalled serplus software with no change.

Using msconfig, i have located the problem to a SERVICE, a Mircosoft service, but i dont know which one???

If i go into Safemode, the problem is not present.

i have created another user, the problem is still present with this new profile.

also i have updated window, no change

Please, any assistance will be greatful..Jeff