The day may come when you suddenly have persistent virus or spyware problems that you cannot seem to get rid of. Perhaps your kids were playing games at questionable websites, or you forgot to update your security programs for a few days.

There are generally 3 ways to tackle your problem. We will look at each of them in turn, from simplest to more complex. I assume you have scanned your computer with all your updated anti-virus and anti-spyware programs, and your Windows is up to date.

1. The first thing to try is Safe Mode. Launching Windows in Safe Mode provides just the bare essentials to run your PC, so it will look a little funny. But it therefore leaves viruses and spyware more vulnerable to attack.

In Windows XP, boot the computer. Before Windows loads, depress F8 for Safe Mode start-up. You may only have a second before Windows loads. Keep depressing F8. If Windows loads, try again after the normal start-up.

On some computers, you might have to press the Delete or Esc key, instead of F8. For earlier versions of Windows, boot the computer. After you hear the first beep (the POST), press and hold the Control key (Ctrl) until you see the menu. Use the up and down arrows to select Safe Mode. Press Enter.

Once the computer is running in safe mode, do all your security scans again. This may solve your problem.

One reason viruses and spyware keep reappearing is because they may have made entries into the Windows Registry. The Registry is a large database, or list, of every single thing on your computer.

To help prevent malware from writing to the Registry, get a custom HOSTS file, to block requests that the spyware be downloaded and installed again. A HOSTS file also helps protect you from spyware. Look on the Internet.

You should also have a backup copy of the Registry, in case it ever gets corrupted. Make a backup when your computer is running with no problems.

To make a backup, do this carefully: Click Start, Run. Type regedit in the box, and click OK. Highlight My Computer if it is not already highlighted.

In Windows XP, click File, Export. Type a name for the backup, such as Registry Backup 1, and click Save. In earlier versions of Windows, click Registry, Export Registry File. The file will be saved in your My Documents folder.

To restore the Registry using your backup copy, click it to open it, then click Yes, OK.

2. If you have had a serious virus or spyware problem and have cleaned your computer, you should delete your Restore Points

So keep all this in mind as you choose your Virus software and prepare for the worst!