cant chdir to maildir

[Lanny Baron]

Hello,
What might cause mail not getting to users in one virtual domain (actually 
the default domain) with send/current saying: 

@400000003b85b2b8265e902c status: local 1/10 remote 0/255
@400000003b85b2b8269fa83c delivery 7: deferral: 
Unable_to_chdir_to_maildir._(#4.2.1)/ 

Any help is apprecicated. 

Thanks,
Lanny