Idle CPU temp suddenly very high

I wrote up this morning, got online to buy some books, and noticed that my CPU temp was at 59 degrees. I shut itdown, let it cool, and when I turned it back on the CPU went straight up to 58 just sitting on desktop.

It took nearly a minute just to open Firefox.

Also, the PC is connected to the network, but browsing times out and Steam won't connect. My WiFi tablet, phone and wired HTPC are having no problems with the network. Could it be related?

I've never seen this happen before. GPU temps are normal (R9 290, in the 40s at idle). Only just shot some compressed air through the CPU cooler last month, so shouldn't be a dust problem. Everything was working just as usual yesterday.

Ambient in my apartment is 28, just a little cooler than yesterday which was 31. And much lower than last week when it was mid 30s.

This is a Xeon 1230v3 with a xigmatek night hawk cooler. Only installed it about 8 months ago, so the thermal paste shouldn't need changing already (surely, I ran a FX4300 for near two years without changing the paste).

Any ideas what has happened?


Stupid. Let this be a warning to anyone who doesn't check their task manager before making an idiot of themselves.

Avast anti-virus was using 99.5% of my CPU. Uninstall, reboot, temps are 32 degrees, internet is working again.

Glad you solved this, trustedinstaller.exe does this to me frequently (awfully shady name for an official update installer).