Recently I have applied the PSU5 and PSU9, in both cases a couple of issues happened when executing the OPatch utility.
The first one, has to do with a runtime error during the execution of the OPatch utility. Suddenly a window pops up saying it cannot find the msvcr71.dll library, this is a module containing standard C library functions such as asprintf, memcpy and cos, it is part of the Microsoft C Runtime Library. The workaround for it was to look for it at one of the previously installed Oracle Homes and copy it to the C:\Windows directory.
The second issue has to do with a file, srvm.jar, which after the OPatch evaluation, it says this file is in use. It looks like the 18.104.22.168.0 version of the OPatch utility cannot identify it is the same utility who is using the file. This is a known issue and is documented in the M.O.S. Note "OPATCH 22.214.171.124.0 LOCKS SRVM.JAR WHEN APPLYING ANY 126.96.36.199 BUNDLE PATCH ON WINDOWS X64 [ID 1446273.1]" This will be fixed in future OPatch versions, and the workaround is to look for a jar file, %ORACLE_HOME%\OPatch\jlib\oracle.opatch.classpath.jar, rename it and retry. Once the OPatch utility is done rename back the file to its original name.
You can use the Microsoft utility Process Explorer to see who is using these files. Just make sure that you exit the utility before relaunching OPatch, otherwise it will misinterpret the locks of the Process Explorer on several oracle related dll's and the list of Oracle dynamic linked libraries in use will be longer.