First, backup your stuff. There's no telling if this won't happen again - and if it does, you may not be able to get back into Windows.
Create a System Repair disk. Go to Start...All Programs...Maintenance...Create a System Repair disc
Dunno if it'll help with Asus System Recovery, but it'll help if there's corruption in the bootup sequence files.
No need to run those just yet - start with the tests in the next paragraph (the first 3 are bootable and don't need Windows).
After that, start with the free diagnostics here: Hardware Diags
At work we run the first 3 on every system that we take in for service.