I'm having this problem on two second hand hp business machines with ... I think discrete graphics but now that I'm writing this I never bothered to check. I'm running Ubuntu on them and they basically run Minecraft and flightgear a few times a day. Not every time, but eventually when either machine attempts to enter suspend mode it will instead crash and stay like this until a manual hard reset. I suspect this is related to certain software running when suspend is initiated but I'm not sure.
I'm not using Ubuntu much myself these days and I've never used a Radeon GPU, any advice or ideas would be appreciated. If anyone wants to dig in I can get hardware info and logs, I'm feeling lazy at the moment.
I have a problem of "unable to suspend user.slice", when using a Virtual Machine.
When I get back from sleep, I see the lockscreen, but after logging in, I have nothing displayed. This might have changed since I haven't set the computer to sleep with that VM in a while.
In my case
REISUBworks.REJand switching tottyalso works... but stuff doesn't work well after that until a restart