Most are saying to check the drivers for updates.
Formatting was also a no go as the problem appeared again.
Some users had this issue when the computer was supposed to sleep or standby
One user said this: Go to the Device Manager and find the "ACPI Lid" driver. Change the driver by selecting the "Volume Control" one from the list of drivers. This may sound stupid but what it does is trick the driver into stop working since Vista won't let you remove it outright. Once you do this, the lid, and everything else works perfectly. <-- Give that a try
Formatting was also a no go as the problem appeared again.
Some users had this issue when the computer was supposed to sleep or standby
One user said this: Go to the Device Manager and find the "ACPI Lid" driver. Change the driver by selecting the "Volume Control" one from the list of drivers. This may sound stupid but what it does is trick the driver into stop working since Vista won't let you remove it outright. Once you do this, the lid, and everything else works perfectly. <-- Give that a try