Error while applying SQL server 2008 SP4

Hi Friends,

I am trying to apply SQL server 2008 SP4 to my instance. I am getting below error after the "check files in use" tab and i am not able to progress further.

When i check in the setupbootstrap log details.txt

File "C:\Program Files\Microsoft SQL Server\100\COM\DISTRIB.exe" has been locked.
 Error: Action "GatherUserSettings" threw an exception during execution

Exception type: System.IndexOutOfRangeException
   Message: 
       Index was outside the bounds of the array.
    Stack: 
         at Microsoft.SqlServer.Configuration.InstallWizard.FilesInUseController.RunLockedFileCheckCompleted(Object sender, RunWorkerCompletedEventArgs e)
2016-03-09 04:32:47 Slp: Watson Bucket 1

I have transactional replication configured in my instances. How should i proceed further? Should i stop SQL server agent service and try patching.

If that is the solution, is it okay to take down SQL agent services before applying SP.

Thanks

Udhayan