Why did Dropbox sync stop working?

Question

Data synchronization

The other day, Dropbox independently updated to version 3. I tried to roll back (I didn’t like the new icons) - it doesn’t let me in, it requires an update to enter. They updated the protocol. Well, I don't think it's fate. I return the third version.
And then I was surprised to find that the folders linked by symbolic links (created via Junction) stopped synchronizing. Everything used to work fine, but now it says "Unable to sync [Directory] (file is currently in use)". Tell me where to dig. Is this a developer bug? Will they fix it soon, is it worth writing to support (or are such letters ignored there)?
OS Windows XP SP3