My computer won't start. Error Code = 0x490

I have a Windows Vista that won't start because of error code 0x490. I checked for memory hardware errors and there was nothing. I tried to use the System Restore option, but it says, "No restore points have been created on your computer's system disk. To create a restore point open System Protection." The I clicked on "System Protection" that was at the end of that quote since it was blue and underlined, like a link, (is it still called a link if it's not to a website? -- Anyway!). After I clicked it, a window came up that said "Your computer is running in a limited diagnostic state. If you use System Restore in this limited state, you cannot undo the restore operation." I then clicked OK, it closes and I'm back to the System Restore window that had the first quote. I guess I can't use System Restore because I can't click "Back" or "Next"; I can only click cancel. I can't run it in safe mode because I can't even get to the boot menu when I restart the computer. What is my next option? Please help!