Just last month an expired antivirus did that. Since Windows Defender has improved we tossed out the AV and went with Defender.
So my internet seems to drop out every 30 minutes for about 5 minutes, I can still talk to people on existing connections like IRC/Skype/Game clients but I can't load any web page.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic