Hoople - 4:40 pm on Jul 9, 2012 (gmt 0)
Depending on the OS there is an option on start-up to roll back changes. It may sound like 'start with last known good settings' (older) or 'restore last saved (previous) configuration' or similar.
More details may get a more detailed response. Sounds like a registry edit may be needed in addition to the driver swap.
Check the motherboard manufacturer's website for a user troubleshooting forum and possibly a down-loadable BIOS update.