Help! CPU Usage @ 100%

I'm using a laptop and when the laptop run solely on batteries, everything is normal, however when i plug the adaptor in, the CPU usage becomes 100% and the process that is causing it is "System". The system would display 99. I just reformat my laptop because of this issue as i thought it was some viruses or spywares but its not.

The adaptor and battery was also tested on different other laptops and it was working fine. I'm curious what could cause this problem, any help would be appreciated dearly.

 

a format may not always remove a virus or spyware. a format only hides information and allows it to be overwritten. avg is a good program to try. also it may also be a heating probelm with your laptop. if the processor is running hot then it will slow. it maybe worth checking for viruses and also making sure your laptop is not getting too hot

 

only thing I can think to do is try getting all windows updates. other than that it sounds like it may be a hardware problem since you reformated which kinda rules out viruses.

good luck

 

To me, this is what rules out a virus (which can survive a format - but not an FDISK)

http://support.microsoft.com/kb/320345
CPU Usage Rises to 100 Percent If You Charge the Battery Slowly While the Computer Is On

 

sorry i forgot to mention that, even if i run the laptop SOLELY on the adaptor, the cpu usage is still @ 100%, and its still reads as the "system" using 99. it can't be any viruses because i've scanned all viruses and spywares using panda internet security already.

regarding the charging issue, even when my battery is full as it is showing green in colour, the cpu usage still reads 100% until i unplug my adaptor and run the laptop solely on batteries then everything will be back to normal..

oh ya, im using windows xp pro edition, if u guys still need any information please let me know.

 

When you say SOLELY on the adaptor, do you mean you are physically removing the battery and running off mains power?

edit:

And which Service Pack for XP?

http://support.microsoft.com/kb/328915
100 percent CPU usage may occur under some battery conditions

 

Yup, running off directly using the main power. Im using microsoft windows xp sp 2

 

OK... but are you physically removing the battery?

 

physically or not i tried both. I think its the motherboard problem, i got it sent down to the service centre and it got fixed already. thanks alot anyway.