Almost using 99% of CPU just using web??

The fan starts running like its under a heavy load, but it isn't, the only thing that I would have up would be Firefox. If I close Firefox my cpu usage under performance would still be 30 or maybe even more sometimes up to 99. But right now the cpu usage has went down to 0-2% and the fan seems to be quiet now.

Also sometimes the System Idle Process will use up 99% or so of my CPU under the processes, I don't know if that affects it or not because the CPU usage is down to 0-2% in the performance tab.

Would standby or hibernate have to do anything with this or do I have a virus that avast has not detected? I also tried the free online scan of Mcaffe, and that didn't pick up anything.

Thanks

Also I should add that the orange light by the wireless and bluetooth constantly blink when this happens. The proper word is escaping my memory right now sorry.

 

When you close Firefox is the process actually stopped in your task monitor? I had similar thing with high CPU load in multiple tab situations in Maxthon and Firefox and that was usually the case. Closing the prog did not necesarily mean I had stopped the task.