TF54000: Cannot update data because the server clock may have been set incorrectly. Contact your Team Foundation Server Administ

i just correct this problem by follow these steps:
1. open database server  where tfs server was installed
2. open database TfsVersionControl
3. Open table tbl_ChangeSet in TfsVersionControl database
4. remove datas where CreationDate lager than the date i have changed on the server

then it's ok, but maybe lost some data, so you can backup data first