As far as I can tell, this is on dapper only.
Current workaround is:
$LD_LIBRARY_PATH=/usr/lib/firefox evolution &
Bugs reports and ubuntuforums thread:
https://launchpad.net/ubuntu/+source/evolution/+bug/56118
https://launchpad.net/ubuntu/+source/firefox/+bug/88990
http://www.ubuntuforums.org/showthread.php?t=373449
Edit: problem solved with [USN-428-2] Firefox regression
Ubuntu 6.06 LTS: firefox 1.5.dfsg+1.5.0.10-0ubuntu0.6.06.2 libnspr4 1.5.dfsg+1.5.0.10-0ubuntu0.6.06.2 libnss3 1.5.dfsg+1.5.0.10-0ubuntu0.6.06.2 USN-428-1 fixed vulnerabilities in Firefox 1.5. However, changes to library paths caused applications depending on libnss3 to fail to start up. This update fixes the problem.
