Provlem with mount and backup

[citrixnl]

I have a Windows 2000 server with Exchange 2003 on it. Everything was working fine untill accidently the rights have changed on the server. The server still works but i cannot backup the server anymore and on a restart the stores are not automatically mounted. On startup i get the the message: error 0xfc01 cannot mount store

And when i try to backup i get the errors:

Event 904
Event 8012

I tried several things but nothing seems to help untill now. Maybe somebody has a clue ?