When ps5ui.dll is gone, the driver is NOT installed.
0x7E is ERROR_MOD_NOT_FOUND.
I do not think this is related to the spooler exploit. The spooler has been a nightmare since forever so that was nothing new.
On the clients, killing the print spooler RPC endpoint is perfectly fine.
I was curious if there are any references to ps5ui.dll in setupapi.dev.log. The file is text based. Use notepad.
Does the issue seem to occur after a Windows Update?
There are two main PS files in c:\Windows\System32\spool\drivers\x64\3\
PSCRIPT5.DLL and PS5UI.DLL
The other files are PSCRIPT.HLP, PSCRIPT.NTF, and PSCRPTE.NTF
Are these other files missing as well?
The Ricoh PCL6 driver uses unidrv.dll and unidrvui.dll. Do these files ever disappear?
I like PS best but if the files do not get deleted for unidrv based driver files that may be a safer route.