I have patched this with a new script for the forum in the 2.3.4.2 release. This issue only affects MS SQL and SqlAzure, if you downloaded mojoPortal 2.3.4.2 previously and are experiencing this sort issue, you can just get the script at /Setup/Applications/forums/SchemaUpgradeScripts/mssql/0.0.1.4.config
Install this script and visit setup page again, it will correct the sort in the stored procedure.
Best,
Joe