Anonymous writes: I am soon to be a single mother. My soon to be ex-husband and I owned a computer store. I only have a working knowledge of computers; he was very good at it. When he left the house, he still was able to enter the PC, and I think he installed a keylogger program on the family computer. I can't do anything on my computer at home for this reason, and was wondering if you would know how I can check this, or delete it from my computer.

Keyloggers are a common form of software and hardware that are used to keep track of everything a user does on a PC: Essentially, every button you press is recorded to a file, which the spy can then access at a later time. All your passwords, and everything else you type, is accessible by the perpetrator. Some keylogger programs can even record occasional pictures or video of the screen. Other variants can take a snapshot of you with your webcam. And yes, they can relay those logs over the internet (though this makes them easier to find).

As you can likely tell, keyloggers represent one of the most serious forms of spyware on a PC, but they are hardly unbeatable. First, most spyware detection and antivirus software should be able to uncover their presence and remove them. If you suspect a keylogger is on your PC, update your antivirus software of choice and give it a full run. Also try a sampling of other spyware killers: My current favorites are Ad-Aware and Spyware Doctor. Both are free (the latter if you get it as part of the Google Pack).

Also, and this is critical, check out your computer for any hardware you didn't connect yourself. Many hardware keyloggers look like thumbdrives and connect to either your USB or keyboard port, often between your computer and your keyboard cable. The device does all the recording and the spy simply collects the device at a later time to access your keystrokes. Spyware detection software may not uncover these devices. See the photo above for an example. They can be very small and hard to detect, so check thoroughly.

If you detect nothing in your spyware hunt but still suspect you have a keylogger (or if you find the keylogger software but are unable to remove it), your best bet is to reformat your hard drive and reinstall Windows from scratch. It's a pain, I know, but you're better safe than sorry in a situation like this. Anti-spyware tools are not perfect and can miss infections. I'd rather advise you to spend a weekend reinstalling software on your computer than potentially give up all your secrets to someone who might use them against you.