Please join the linux-power mailing list if you are interested in contributing. Get the latest 2.4.0 kernel. When configuring the kernel, select three things. You will probably want to get the latest ACPI patch from this website, as what's in the kernel may lag our releases. Many systems have incomplete or buggy ACPI support.
Some laptops have well-known issues.
Make sure you are running the latest BIOS for your machine. If your machine isn't of a fairly recent vintage, it may not support ACPI at all. This version has many diagnostic outputs, which will aid in debugging. The output from dmesg. Please either attach it to your message, or indicate a location where it may be downloaded.