I just bought this computer less than a month ago. I have made no modifications to it. None of the basic programs will work (calculator, calendar, etc.) and I cannot install any plug and play devices, they will run, but then in device manager just be the little yellow exclamation mark. When I try to update drivers it always gives me,"windows encountered a problem installing the driver software for your device -whatever device I am trying to update- systems cannot find specified file". A couple weeks ago I updated to 8.1 (on accident, just by restarting my computer) and when it came up, none of the devices worked still, but now my audio doesn't work. It doesn't recognize my speakers or anything. I have an ASUS M51AD-805. I've tried disabling my virus protection, removing signature requirement for drivers, changing my resolution, and so many other things. I'm getting frustrated and any help would be great.

Did you install audio drivers for Window 8.1? 

please check with ASUS on this., they will be able to help you with driver compatibility

Hi,

Error shows System cannot find specified file some important files might got missing \corrupted or got deleted by accident, I suggest you run sfc/scannow check and fix the corrupted files.
Check if this issue happens in other user accounts, if no, then you might get a total corrupted user profile, try fix this by following this link
http://windows.microsoft.com/en-in/windows/fix-corrupted-user-profile#1TC=windows-7

Since this is a new bought computer, it should be still under warranty, you can take it to the vender's repair shop.
It is also recommended to contact this support
http://www.asus.com/Desktops/M51AD/HelpDesk/

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Hi,

Hows everything going?
If you could update us at your convenience that would be wonderful.