Definition updates using UNC shares fail with 0x80070008 [Not enough storage is available to process this command]. This can happen when all of the following conditions are true:
The computer on which you are updating definitions has either a Windows XP or Windows Server 2003 operating system
Security Bulletin MS09-012 is installed
There is sufficient disk space for the definitions available on a fixed hard disk
When you configure the definition updates to utilize UNC shares, the updates run in the context of the NetworkService account. During update, the NetworkService account attempts to access the \?? WMI namespace and MS09-012 enforces isolation between WMI providers and processes that run under the NetworkService account. Therefore, the \?? WMI namespace is inaccessible after security update MS09-012 (KB 956572) is installed.
To resolve this issue, install the fix described in the following article:
978835 Service cannot access the \?? namespace in Windows XP