Windows – ngen.exe is constantly using CPU

cpu usagengenwindowswindows 7

I recently installed Windows 7. This was a clean install (i.e. not an upgrade from another version of Windows), but I did install a bunch of other programs. All mainstream applications – nothing wacky.

Since then, my CPU usage has been constantly at around 50%.

Task Manager shows me that ngen.exe is the culprit. It's not a long-running task: I can see that it gets a new PID at least once a second, so I guess something is constantly triggering it.

It does it all the time, even when I have no applications running.

Has anyone else seen this? How do I find out what's causing this?

Best Answer

Following Isxek's advice, I used Process Explorer to see what's going on. I found this:

enter image description here

Processes that are ending are highlighted red; ones just starting are green. This shows that ngen.exe is constantly ending and being restarted. From the graph at the top you can see it runs for about one second each time.

As Jim B says, netfxupdate.exe is working its way through the .NET framework. Mine had been going for several weeks, so for some reason it looks like it had got stuck on something and wasn't making any progress.

Using regedit, I found the entry that starts netfxupdate.exe whenever I start up my PC:

enter image description here

It looks like it's stuck on the .NET 1.1 libraries for some reason. I'm a .NET developer and some of my code runs on .NET 1.1. It all seems to be working fine, so I removed this entry from the registry and rebooted my machine.

It's been a couple of days now with no problems (even when developing against .NET 1.1), so I'm happy with this solution.

Related Question