Remote Desktop keeps disconnecting

A friend needs to connect with me using Remote Desktop. She sent an e-mail
invite yesterday and that worked fine for a while. I was able to Take
Control of her computer for 15 minutes or so before I got a Disconnected
message. This happened twice.

Today we tried again and this time our respective computers stayed connected
for not longer than 30 seconds; this happened over and over.

I have Windows XP Pro SP2; she has, I believe, XP Home SP2.

Anyone know what could be causing it? We both have a broadband connection.
We both turn off our respective firewall apps because it doesn't seem to
work at all with either on. What I see is that my Control ability suddenly
stops but I can still see activity on her desktop for a few seconds (like if
I send a windows live messenger message real fast) then the Remote Desktop
interface suddenly shrinks and reports that I've been disconnected.

Also, as a side issue, the request via messenger doesn't seem to work; only
through Start | Help and Support | Email invite.

Thanks.