TFS howler: password changes while VS is open – you lose the ability to check in until you restart VS. Bug exists in 2005 and 2008
TFS is a very different version control system. That is not a good thing. It seems clunky and ill thought out. Unfortunately I have to use it…
It assumes that you are using visual studio (unless you use the excellent tfs bridge/ tortoise svn).
You need to save everything before you can check in.