If a file is solidified or write-protected and process is not an Updater, modifications to file will be blocked. But here the process wriing on the file is 'system' which is not recommended as an Updater.
You can configure the DLLs to remain unsolidified (to allow modification) and add the same as authorized by name (to allow execution).
To prevent the file from solidification:
sadmin skiplist add -a <dll>
Could you give more details on the names of the DLLs, the application to which they belong and what workflow is causing the DLL to be modified (application update, etc)?
While that command appears to only be available in App. Control 6.0, it did lead me to this article. I've implemented the workaround using the registry modification listed on the link below. We will see if this solves the issue.
Sadmin skiplist add -d \GenericFolder\Something.dll
Sadmin skiplist add -d \GenericFolder\Something2.dll
This has worked for my write denied exclusions.
You can also push this out via ePO as a Solidcore task.