For me the problem was apci.sys. In device manager look for battery. I un-installed
everything except ms composite now I have no problems. This is on Acer Aspire 1640.
What is wrong here.
Microsoft doesn't make Vista (windows 7) drivers
the System Management Bus Host Controller (ACPI0001)
the Smart Battery Subsystem (ACPI0002)
Acer isn't going to make a bios upgrade for this laptop
So check out this site if you want to create your own bios upgrade.... Acer Latops