I have a recent x86_64 snapshot running on a ThinkPad, and it locks up every once in a while. I just noticed that it’s just the graphic interface, and I can still access via ssh from another host. “ps” shows everything is still there, but the thing that was running in a Terminal window has stopped doing its job - as of, apparently, the moment I touched the keyboard, so maybe it happens when there’s UI device input after it has been idle for a time.
On UNIX, I’d be getting more details out of ps - if anything is drawing a lot of CPU, RAM, anything stuck in “device wait” status. Does Haiku have any of that?
Did you try control-alt-delete… this will get you the task killer and you can for instance restart some of the services and perhaps get it going again graphically.
You can try killing the deskbar and or app server and restarting them (think they may restart automatically).
From your ssh connection, you can of course use ps, top, and the usual tools for looking at the state of processes. One thing you can try is disabling the screensaver and screen powersaving, in case it is something going wrong with trying to put the display to sleep.