What's with error 1450?

Hello all: running xp with sp1 installed. I have it networked (occasionally)
with my laptop via a crossover cable, network card to network card. I don't
share the internet connection (dial-up). All's been fine till recently. I
leave the desktop on all the time and dial up when I want to send/receive
e-mail/news. Now, after it's been up for over 1 day when I ask it to dial up
I get this error, 'TCP/IP CP reported error 1450. Insufficient system
resources to complete requested service'. I haven't installed or changed
anything so I don't understand what's wrong. If I reboot it dials up fine.
Any ideas, please?
thanks
brian