Real malware is generally designed not to be noticed. The people who write these programs don’t want you to clean them off your computer. But if you know what to look for, you can recognize a symptom that might be caused by malware.
Here are some symptoms that could suggest foul play.
Sudden poor performance.
If your PC is running slower than it used to, or it seems to be running an awful lot of stuff in the background, malware could be the cause.
Standard maintenance programs don’t work.
Malware will often protect itself by disabling programs that might help you identify and remove it. So if programs like Windows Update, Task Manager, your antivirus program, System Restore, fail to work, you have reason to be suspicious.
Unwanted toolbars that won’t go away.
All sorts of programs might install a new toolbar into your browser, and usually, it’s no more than a temporary annoyance. But if you can’t turn off the toolbar, or you do turn it off and it soon reappears, there’s something more sinister at work.
Your home and search pages change.
This is very much like the toolbar problem. If your homepage changes to something you don’t want, and you change it back, but your change doesn’t last, something is running that you have to stop.