I still see far too often the case where users see a message that pops up on their screen saying - Call this number to clean your pc.  I say one word - NOOOOOO! 
You have to be more cautious than to 1) call some random number and 2) let someone you don't know give you any guidance on your pc.  It's synonymous of driving down a road and having a stranger flag you and you simply pull over and say - GET IN.  Of course you wouldn't do that.  The next time you see a message pop up on your screen saying to dial a number - DON'T CALL THEM BACK! Call Us - your local reliable and reputable computer service provider.

Comcast performs unannounced random upgrades to their modems and refuses to establish a consistent schedule whereby their customers (many of my clients) can work around and schedule their BUSINESS activities accordingly.  As a result, customers experience EXTREMELY DISRUPTIVE outages during the peak hours of their production.  I have pleaded with Comcast to take a more responsible approach like other providers.  As a result - YOU SHOULD KNOW - that is important to reboot your Comcast modem once a month. This may be a perceived nuisance, but since it avoids peak production disruption, it's worth it - REBOOT MODEM ONCE  A MONTH.

Far too many people are still falling for the most obvious of scams.  Scammers prey on your FEAR! They feel if they can get you emotionally trapped by telling something BAD WILL HAPPEN, then you will fork over all your personal information, including banking information.  PROVE THEM WRONG!

Keys to Avoiding Scammers
Tell them you're busy AND ask for a call-back number
If they're number is blocked, then don't answer
Don't provide personal information over the phone
Don't provide personal information through a solicited email
Do not - Do not - Call numbers just because it shows up on a pop-up screen on your pc
If you get a message that says you have a virus OR your pc has been compromised, then call a LOCAL CREDIBLE Co.

I spend a lot of time assisting users on how to recover from pcs.  #1 is always Reboot (usually holding down the power button for 5 seconds. #2 Start system in Safe Mode to determine is something software related is causing OS conflict, #3 my goto usually after about of 30 minutes to 1 hour of troubleshooting is a system restore.  I'm usually back in business, by then.  I hope this helps you!!!