Backup error (Veritas backup Exec v.10) on Windows 2k3 SP2

I am using Veritas Backup Exec v.10 as my backup software on Windows 2003 Server (SP2), in an AD environment. Recently some backup jobs dont finish successuflly. They (jobs) either fail with exceptions or just failed. The error log gives me this:
AOFO: Initialization failure on: "\\Servername\D:". Advanced Open File Option used: Microsoft Volume Shadow Copy Service (VSS).
Snapshot provider reports "Out of memory".

AOFO: Initialization failure on: "\\Servername\E:". Advanced Open File Option used: Microsoft Volume Shadow Copy Service (VSS).
Snapshot provider reports "Out of memory".

AOFO: Initialization failure on: "Servername". Advanced Open File Option used: Microsoft Volume Shadow Copy Service (VSS).
Snapshot provider reports "Out of memory".
The following volumes are dependent on resource: "E:" .

AOFO: Initialization failure on: "\\Servername\Shadow?Copy?Components". Advanced Open File Option used: Microsoft Volume Shadow Copy Service (VSS).
Snapshot provider reports "Out of memory".
The following volumes are dependent on resource: "C:" .
Network control connection is established between 172.18.212.231:1756 <--> 172.18.212.249:10000
Network data connection is established between  172.18.212.231:1778 <--> 172.18.212.249:1173

I need to resolve this soon.