The laptop is a Gateway purchased in August, 2007. ACPI is enabled through VASM.
I have to get this fixed or I won't use VL on this laptop. The difference in how hot it gets when running Vista as compared to running 5.9 Standard is astonishing. I did Web browsing and some other tasks for about three hours in Vista today and the case was cool to the touch. And while hot air could be felt at the fan outlet, the fan ran very infrequently. I then rebooted to VL and the case was cool and fan not running at the start of my session, but after about 15 minutes the case is quite warm, the fan is running full tilt and louder than it ever is in Vista, very hot air is streaming out of the fan outlet, and the palm rest is getting warm.
I wondered why I hadn't noticed this before and then I realized that from the time VL 5.9 was up to Release Candidates, I nearly always ran Linux on the laptop and didn't used Vista often or for very long. The fan isn't loud and I probably assumed the laptop was running in VL the way it was supposed to. It wasn't until I needed to run Vista a few days ago for a more extended period that I noticed how much cooler and quieter the laptop was running.
The laptop never got so hot that it turned off by itself, but I hope I haven't shortened its life by running it so hot for so many months.
I'll be very grateful for any suggestions on how to make it run right.