do not respond to "your machine is infected. call this number" website scam

usual exploit
rogue web page opens with warnings
asked to call scammers

As a general rule be suspicious of any unknown agency suddenly taking an interest in your computer asking you to call them to get help.

If you are going to call anyone, call someone you trust and know is competent.

In this case, the client called ISITZEN (unfortunately after a brief interaction with the scammers). Evidence of malware installed by the representative was found, as was some questionable remote control software.. Removed malware and and rogue GoToMeeting software. Monitoring closely for the next week.