It is typical issue with Lion and Mountain Lion especially.
Try firstly just a restart of the TC.. ie pull the power ..count to 10.. plug the power back.
If that is not enough.. do a full network restart.. with everything off.. restart modem.. TC.. computers etc. 2min gap.
It might help if you change the names of everything to SMB standard in the TC.
ie short, no spaces, pure alphanumeric.
And fix the wireless channels.. if you use wireless.