Here is the 11.11 installer if you want to go back to that version and test the theory that the problem started with 11.12. (If 11.11 works, it's worth reinstalling 11.12 and rebooting again, in case it was just coincidence. Sometimes just rebooting for the update causes queued-up changes from other things to be applied to the machine whose effects are then attributed to the update.)
[ul][li]DOpusInstall_11.11_x64.exe[/li]
[li]DOpusInstall_11.11_x86.exe[/li][/ul]
If the problem happens with both 11.11 and 11.12 then, without any other information, these guides are the best place to start:
[ul][li]Crash, exit or high CPU usage when viewing certain directories[/li]
[li]Crash, exit or high CPU usage when right-clicking certain files[/li]
[li]How to find components causing high CPU usage[/li]
[li]How to find components causing memory leaks[/li]
[li]General slowdown or instability investigation steps[/li][/ul]