[Evolution] gnome-keyring and Evolution take all my CPU

[Peter Saffrey <pzs dcs gla ac uk>]

My Evolution installation (2.22.2 on Ubuntu 8.04) regularly grabs most
of the processor, split between gnome-keyring-daemon (40%), evolution
(25%) and evolution-exchange (15%). This usually happens after I start
writing a message (like this one). Performance doesn't seem to suffer
too much, but it's annoying because my load manager is all blue when I'm
not really doing anything.

I can fix the problem by restarting Evolution, although it takes around
30 seconds for Evolution to shut down unless I hard kill it.

Interestingly, this only happens on my home machine. My work machine,
with has an identical Ubuntu installation, does not have the same
problem. Possibly this is due to it being on the same network as the
Exchange server.

Any ideas?

Peter