The problem can be corrected by upgrading the affected package to version 1:1.0.0-1ubuntu1.6 (for Ubuntu 4.10), or 1:1.1.4-1ubuntu4.3 (for Ubuntu 5.04). After doing a standard system upgrade you need to restart Gaim to effect the necessary changes.
Details follow:
A remote Denial of Service vulnerability was discovered in Gaim. A remote attacker could crash the Gaim client of an MSN user by sending a specially crafted MSN package which states an invalid body length in the header.