Computer freezes when I open task manager.

@Mudnail

I can confirm leaving Outlook 365 closed did help, it took longer for Task Manager to start acting crazy and slowing down the computer down.  I was able to actually close it to restore full use of the computer when it started.  (It took about 10-20 minutes before the computer started to hiccup with it open.)  So it's a good start....but not perfect in my testing.

Fingers crossed that RS4, whatever it ends up being called has a hidden fix that addresses this as obviously Microsoft isn't helping.

Others have mentioned Office 365 here, I wanted to mention that I have done some testing and have confirmed that if Outlook for Office 365 is open when I open task manager, the cursor becomes laggy and the machine will sometimes come to a complete halt, however if I close Outlook first, task manager will open without issue. I tried the same thing with Word, but as long as Outlook is closed Task Manager seems to open fine. I hope this helps.

Today for the firs time it's showing up at client sites. On the plus side, at least I don't need to waste a lot of time debugging it, but even average users are used to opening up task manager if a program hangs. So it's not practical to tell them not to use task manager. 

Ah ok!

Nah I feel the same, I don't really wanna tell my end-users that they need a third-party program to "get around" the problem.

This should not be needed in a practical matter. Even if it's a working solution for the time being.

Go, go Microsoft! I actually downgraded myself to 1703 yesterday and my own workstation is feeling so much better overall. Blocked 1709 for 80days for the moment.

Today for the firs time it's showing up at client sites. On the plus side, at least I don't need to waste a lot of time debugging it, but even average users are used to opening up task manager if a program hangs. So it's not practical to tell them not to use task manager.

I've received suggestions from Microsoft Support to use the Feedback Hub to provide feedback on this issue by replicating it with the "Collect Diagnostics" option running.  However, like stated before...the computer freezes, so there's no way to submit the feedback.  The system locks before I can.

Funny enough, I was talking with another person in IT yesterday and mentioned my frustration with this bug and he said that he's had the issue as well and just moved to using Process Explorer.

I'm beginning to think this issue is a lot more prevalent than the limited number of people here reporting it would make it seem.  Many just look for alternate solutions, likely because they're tired of the same suggestions for every issues....  SFC, DISM, Refresh, Reinstall.  You'd think with all the telemetry data that MSFT collects by default, they'd see the problem if they'd just look.

Fingers crossed that the 3/18 maybe called "Spring Creators Update" provides some resolution to this.....