Just tried to connect to a share on an XP Pro SP3 PC from a Windows 7 machine. It always worked in the past, but this time I got “Not enough server storage is available to process this command”. The ONLY thing that had changed on the XP machine was that I had upgraded from Avast 4 to 5.
A quick google suggested that this may due to a missing registry entry, IRPStackSize. It also indicated that this problem goes back a number of years and is commonly introduced by AV progs.
I made the change, rebooted, and now things are back to normal.
Here is an easy to follow guide to make this change, if anyone cares: http://www.tips4pc.com/Computer-repair/i_get_an_error_that_says.htm
Not sure what Avast did, but this fixed things.