OS X Mojave: Applications start to hang after a while

Dear Community,

I own an iMac Pro 2017 (10 Core, 32GB of RAM, Vega 64) with OS X Mojave (10.14.3) and up and until now, I have been very happy with it.

However, recently I'm having this peculiar problem: A few hours after booting OS X (usually I work during that time, Java programming, MS office etc.), random applications start to hang for no apparent reason. That is, I cannot bring them to the foreground anymore and the only way to end them, is to use force quit. Usually, I have different applications open at the same time such as Safari, Chrome, Terminal, Microsoft Outlook, Whats App Messenger, Source Tree, IntelliJ etc. I'd say, the problem always starts with a different one.

After that, it gets really strange: One by one, applications refuse to work and/or to start-up. Once I have force-quit and restarted them, they keep on jumping in the dock but they won't become active anymore. It's like the problem is spreading from a single application to the rest until the entire system is completely unusable - even the Finder gets affected after a while.

The only way to fix the issue is to force-reboot the computer (power button). A normal reboot won't work, because the system hangs. However, after the reboot, everything seems to be fine again for a few hours until what I've described starts again.

I've been using Macs for quite some time now and I also own a Mac Book Pro with the same OS and pretty much the same applications. But I have never encountered a problem quite similar as the one I've just described. Does anyone have similar issues? Or does somebody have an idea what might be causing this problem?

Any help would be very much appreciated!

Kind regards,

Ralph