[whpalmer4]

Sync the things once a week and you won't have the complaints. Or are you saying that these machines go more than a week without being on?

If you have a client that you really don't expect to use for a while, you could simply delete its registration (after syncing it, of course). Then when you need it, turn sync back on and when it complains that the files don't appear to match any longer, be sure to select the server or remote copy.

There's no readily apparent means to change that warning interval. Use Help->Send Feedback to request one.