Windows Live Messenger using large amount of VM on Vista

I have an Acer Aspire 5920G laptop running Windows Vista Home Premium with
2GB RAM. I have been having regular problems with it running out of virtual
memory which I think I have now traced to an issue with Windows Live
Messenger version 8.5.1302.1018.

When I load Messenger my virtual memory usage keeps increasing until it hits
maximum values and I have to reboot the machine. I have tried setting large
amounts of system VM and also tried letting Windows set its own VM size but I
still have the same result (sooner or later). When Messenger is loaded I can
use Task Manager to monitor the VM usage and can see it getting ever larger.
Using Process Explorer I can also see that Messenger is showing very large
numbers of page faults. If I close Messenger then the memory stays in use
and the Messenger process remains visible in Process Explorer but if I then
Kill the process using Process Explorer the virtual memory usage immediately
shrinks back to a reasonable level (around 2GB).

Is this a known problem with Messenger on Vista? Is there anything I can do
as it is becoming a nuisance!

Is there an alternative Instant Messaging client I could use instead on
Vista?

Further to my previous message, I have been monitoring it some more and even
when I just load Windows Live Messenger but do not sign in the same problem
occurs. I have just left it sitting there watching task manager and doing
nothing else on the computer and working set memory usage for Messenger just
keeps increasing along with page faults and also handles. For Handles, in
particular, there are now over 24,000 shown against the Messenger process
(increasing rapidly) compared with only 399 for the process with the next
largest number. Surely this can't be right!