Had a problem this morning with 4.0b3, I restarted the webserver and it wouldn't come back up, I had to rollback to 3.3.22 manually (since the web interface didn't work).
If I try to upgrade to it again, then it works fine until it's restarted and then it fails again, a little snippet from the error log is below,
2008-12-03 10:03:16.209 [NOTICE] Loading LiteSpeed/4.0b3 Standard ...
2008-12-03 10:03:16.322 [NOTICE] [ADMIN] server socket: uds://opt/lsws/admin/tmp/admin.sock.7414
2008-12-03 10:03:16.322 [NOTICE] Loading configuration from /opt/lsws/conf/httpd_config.xml ...
2008-12-03 10:03:16.324 [INFO] old priority: 0, new priority: 0
2008-12-03 10:03:16.324 [INFO] [config:server:basic] For better obscurity, server version number is hidden in the response header.
2008-12-03 10:03:16.666 [ERROR] HttpListener::start(): Can't listen at address adminListener: Address already in use!
2008-12-03 10:03:16.666 [ERROR] HttpServer::addListener(adminListener) failed to create new listener
2008-12-03 10:03:16.666 [ERROR] [config:admin:listener:adminListener] failed to start listener on address *:7080!
2008-12-03 10:03:16.666 [ERROR] [config:admin:listener] No listener is available for admin virtual host!
2008-12-03 10:03:16.667 [ERROR] Fatal error in configuration, exit!