Hi, it's not a common problem I've heard of and don't have a quick and easy answer, so you may just want to discuss with your local ASUS support if necessary too for any better ideas.
http://www.asus.com/support/callus1. If you still have time to return the unit to the store, you may want to do this before it's too late just in case it's a hardware problem.
2. If you don't mind erasing Windows and starting over, try this if it will not be too painful just to eliminate any software issues. Otherwise, you might consider trying System Restore if you have any earlier restore points available when everything was working.
3. Don't expect this will make much difference and may not be worth the trouble, but you might try just reloading the default bios settings.
Hopefully we can get some better ideas from others.
Good luck!