|It could be coincidence that you had this pop-up and a few days later you are having problems. If it is simply coincidence, then it could be a hardware issue like a memory module, your power supply, or a hard drive issue. I'm betting on it being a nasty you got and the pop-up was 'cross wired' so when you X'ed it out, you started it or gave it permission.|
Since you cannot boot to windows at all, you should try to eliminate hardware as the issue first (otherwise you might reload windows for no reason and risk your data). There are some utilities you can download on another XP machine and create bootable floppies or CD's to test some of your hardware.
1- First go into your BIOS - to prove you have some access and to set your new boot order to boot from your created disks.
2- Memtest - Memory testing utility - if it fails to complete all tests or freezes, see if you have more than one memory stick and try them one at a time, replace as needed. (If changing memory or pulling either stick doesn't help, you could have a power supply issue)
3- A Disk testing tool from your hard drive manufacturer. (needs working memory to operate)
If you find a problem, then you should be able to fix it. If you can operate both tests, then your power supply should be able to at least start up windows.
4- Use a Linux disk to 'boot from disk' (not install) as a final hardware test and to save any files you need that might not be backed up.
5- If all hardware works, then windows is corrupted. you can try to repair, but then you will still have the nasty to deal with. I would prefer (if all is backed up and you have reinstall medium for all of your programs) to just format and reinstall windows for a clean start.
Post back results and anything you don't understand.