Rayxue,
This is very general error we get during check-in. There can be many reasons so it difficult to give you some specifics but you can check for some normal errors waht we do like
-Object you are trying to check was modified on other Fat client and you are trying to check-in from some other Fat client
-Network failure
-CNC setup issue on your Fat client
-Object corrupted
-Write /access rights on E1 folder
Also check the logs on tis object which can give you some more details of failure.
Thanks,
Chan