had a problem recently where i couldnt do anything network related over my pptp connection to home.
a simple ping from the command line errored with this.
ibook:~ karl$ ping tweakers.net
PING tweakers.net (213.239.154.35): 56 data bytes
ping: sendto: Cannot allocate memory
ping: sendto: Cannot allocate memory
ping: sendto: Cannot allocate memory
^C
--- tweakers.net ping statistics ---
3 packets transmitted, 0 packets received, 100% packet loss
also mail was bringing up a similar error when i tried to get new mail.
i found the solution here - http://www.maclive.net/sid/132
ran a permission fix and all appeared to be ok...
vertikar.net
http://www.vertikar.net/article.php?story=20080417134949558