this happens whenever FolderSize is refreshing its column while retrieving folders size.
I often take advantage of the Address bar, and FolderSize - a really useful app - let it impossibile to use.
so, I had to disable it waiting for a suggestion or a fix.
thank you and respect from Rome, Italy.
I hope you've tried it out again since then, because this bug was fixed in 2.3! Really, more of a workaround for poor Explorer behaviour. The columns don't update if they can determine that the address bar has the focus.