Exchange 2003 Blank mailbox store when creating new user

[chrisjako]

Hi Peeps,

 

Got a strange problem i'm having issues with finding the solution for on google, we have an exchange 2003 server and when i try create a new user in active directory the dropdown box for the mailbox store is blank and it won't let me continue - yet the server is running fine and everyone can still access their emails

 

I think it may be a permission problem in security rights, anyone else come across this issue?