Error with Drafts: Object Not Connected to Server (Outlook 2003)

[agility]

I'm using Outlook 2003, and work from home, connecting to my company's
exchange server via VPN (encryption, firewalls, etc.). I use Word as the
email editor.

If I draft an email, put in recipient addresses, and then leave it in draft
for a little while (minutes), I get a window that says "object not connected
to server". At that point, the recipient email addresses go away, and I have
to start the draft over from scratch.

Any ideas how I can keep this from happening?

Thanks!