In some cases, you may be browsing the Internet and come across a Pop-Up window that tells you that "Your computer is unsafe and may have infections. Click here to scan now" -OR- it may say something like "You Computer is infected with 'x' amount of Viruses or Trojans. Click here now to do a complete scan." In some instances, clicking on ok is giving permission to run the software, which in fact IS the actual infection. It is always best to not Panic and click on anything at that point. This is why it is sometimes called PanicWare. Simply press CTRL+ALT+DELETE and select Task Manager and go to the applications tab. Find Internet Explorer and click on the "End Process" button for all instances of Internet Explorer. Once it is closed, 80% of the time, the symptoms go away and you are ok. Just don't return to the site where you last had that happen!!!
Also, sometimes it does not matter if you don't click on the PanicWare Pop Up box, it's too late. The infection has already been installed on your machine and you will know it because it will keep pestering you to buy some software to fix it or try to get you to run a scan.
Either way, It is BEST POLICY to contact your IT Services Help Desk and let one of us know that you need your computer looked at. Ohterwise, your machine could suffer from process degridation - slowness.