I truly love Offline Files (client side caching - CSC) on Windows machines, particularly in combination with Folder Redirection and DFS: in my setup, I have My Documents redirected to a DFS domain root and cache all the documents I typically need, when working disconnected.

Recently, however, Offline Files was quite unpredictable and would not cache any new files. There were mostly two error messages, one complaining about the system being in last-known-good configuration (system error code 1074, ERROR_ALREADY_RUNNING_LKG) and another complaining about the file not existing.

I looked around, but found not too much help, except a link describing csccmd.exe (from the Server Support Tools) and a recommendation to do all kinds of nasty things to your Offline Files configuration.

What I did was this:

1. I removed all local copies - there was one broken link that could not get removed.

2. I first disabled Offline Files with  csccmd.exe /disable

3. Reboot into Safe Mode and delete all content under %SystemRoot%\CSC

4. Reboot again and re-enable Offline Files.

After this, you need to re-initialize your Offline Files configuration, but at least all errors were gone.