SP2: High power consumption after standby

Hi all
I got some problems after installing service pack 2. I hope you can
help me with this one:

I have an intel centrino laptop with windows xp professional and
recently installed service pack 2 on it.

Under normal circumstances, the laptop does not get very hot, and does
not turn on the fans.

Now, whenever it wakes up from standby or hibernation, it will get very
hot and run the fans almost constantly, with greatly increased noise
and battery consumption. Only after a reset will the power consumption
be back to normal.

This will happen even if no programs are runnning, and the task manager
reports almost no processor activity, or memory access. No unusual disc
access either.

Using the SpeedswitchXP utility I found out that before standby, the
processor speed will always stay below 600Mhz. After waking up, the
speed will frequently spike to 1396Mhz.
The problem persists with or without SpeedswitchXP runnning.

How can I fix this?

Thanks for any help