Scam popup, fake Microsoft support.
Active 12:00 PM EST
Source: PopupDB so it will probably be flooded out soon. Get 'em while you can!
EDIT - They call back from spoofed (800) 940-7624.
Another one: (888) 351-6176
Seems to be the same group.
Source: PopupDB
Number taken down
The 2598 number no longer works but the good news is that 1-888-614-2599 still works.
Edit: The 2599 number was being spoofed, and now goes to a college admissions office. So please disregard.