I have a problem with my sound drivers.I have win 7 pro 64bit and the sound drivers are a huge problems.When windows start sound doesn't work.The only solution I have found to that problem is installing the drivers and not rebooting since this makes sound work until I shut down the pc.After that when I boot sound disappears again. The drivers are the latest from asus website.
More about :problem sound drivers asus p7p55d win pro 64bit
The only thing I can tell you is to uninstall the drivers. Then run one of those registry cleaners like CCleaner so it will delete the residue from the REGISTRY. Next look in the hardware list for the sound device...if still listed after uninstalling and then delete it from the list. Reboot and Windows will detect it as new hardware...from there it will of course try to install drivers on its own...that's when you redirect it to the official drivers for your hardware.
That's all I can tell you would normally work for me. If you have the original system drivers...I'd go with those then do an update.
ps: once you get it fixed...i strongly recommend you use one of those driver back up software programs...I do that myself because they will allow you to reinstall previous drivers rather than do an entire system restore.