Exchange 2003 can give a lot of errors when the database is getting to big.
To solve some of those errors you can try to defrag the database.
First run an offline drag using the tools ESEUTIL ( it’s buildin exchange 2003 )
Open your command prompt and navigate to the folder of the exchange server.
Enter the following commands:
eseutil /d ” full patch to your database file most times it is the biggest EDB file ”
isinteg -s SERVERNAME -fix -test ALLTESTS