Here are a few basic security tips & tricks that you can use to better protect yourself from viruses and malware.
I've begun to see incoming calls on Skype claiming to be an alert service, and urging you go to a website to download something to protect your computer. Because, according to them, your computer is unprotected. This is a totally bogus ploy from a malicious website attempting to trick you into going to their site, which is most likely loaded with hacks that will try everything they know of, to hijack your computer. This may be done through an un-patched (not up-to-date) computer, or by convincing you to download their so-called "fix". DON'T do it!
Just report them by clicking on "Conversation" at the top of the Skype window, selecting "Block...", marking the "Report Abuse" checkbox, and submit it. This will block that user from contacting you again, and alert Skype that they are a problem. Though, the malicious user will undoubtedly create another account and continue under that new username, at least you will now be on-guard for this type of trick.
The best computer security is user behavior - always be skeptical of any unsolicited so-called "help" for your computer.
There has been a number of reports of people receiving a phone call in which the caller claims to be from "Windows Support". The caller claims that they have detected problems on your computer. To "demonstrate" it, the caller will have you open the system logs (which will always contain reports of errors on your system) and tell you that the errors that appear there are proof that your system has a virus. This is not proof of virus activity.
If the caller is successful in tricking the victim into believing that they are there to "help", they will direct the computer user to download a file that is supposed to clean the virus. But, that file is the virus. Or they may request remote access. If the user does allow them to remote into the computer, that's when they will install the malware.
Don't be fooled by this latest technique to infect your computer. Just tell them that you're on to them, and hang up.