Answering your individual emails about offline files is a thankless task, since (a) I’m not tech support, so you’re not going to get any kind of “official” response, (b) I don’t scale out, so other readers of this blog won’t benefit from any pearls of wisdom that I do happen to generate, and (c) I’m not even on the CSC team and I certainly didn’t write the FAQ, as its true author Dave always likes to remind me :-). So before you email me any more questions, bear in mind that I’m more likely to post ’em here than to answer you in email. Like so:

Q: Every time that mobsync.exe starts, my CPU utilization goes to 50% or so. Should sync'ing be this CPU intensive?
A: Yes. It’s touching every file that it can, to compare the version on the server with version in the local cache. And it’s doing this as quickly as it possibly can.

Q: How can I prevent certain files from being cached?
A: You can add filenames or suffixes to an “exclusion list” that is controlled via Group Policy. Specifically, Computer Configuration->Adminstrative Templates->Network->Offline Files->Files Not Cache, whose default value is "“*.SLM;*.MDB;*.LDB;*.MDW;*.MDE;*.PST;*.DB?"

Q: How do I stop it bitching about the files that I’ve excluded?
A: Add those filenames to one of the two “stop bitching about these excluded files” registry keys, HKLM\...\NetCache\ExclusionErrorSuppressionList and HKCU\...\NetCache\ExclusionErrorSuppressionList. All values in these keys are treated as filenames (value and value type are ignored); at runtime the lists under HKLM and HKCU are merged into a single list, and any files whose names match somewhere in the list do not generate an error message if they cannot be synchronized.

Q: Are they really treated as just filenames?
A: No, they’re actually treated as filename specifications, with some limited wildcarding, but Dave didn’t derive a full BNF grammar in his FAQ, and I’m not about to do so from his examples :-)

Q: My offline files setting is still resetting itself after reboot! What gives?
A: If you’ve gone through the five checks and made sure that none of them apply to you, then you’ve probably hit one of the other failure checks that is not specifically exposed in the UI but can still stop offline files from being enabled. Update: Try these reader-contributed solutions to the problem, and let me know if they work!

Edit: I've turned off comments on this thread - if you have a question, please go here instead.