Reboot stucks at reached target.shutdown

When reboot SLES the server stucks and stopped during shown “reached target.shutdown” at TTY. The only way to recover is to power off/on. But this is not possible via remote …
There is no difference when use “reboot” , or shutdown -r now".

But it seems the this behavior is only if the host was up a few weeks.

What I should check?

BTW: This is occours with more then one host. All of them are VM (ESX)