Getting the same error on a SQL 2005 (9.00.3042 - Developer Edition) server. Was working fine a few weeks ago. Nothing I know of has changed, and now getting the failed to login error:

Msg 49999, Level 19, State 1, Line 0

Failed to login to SQL Server

Have tried reinstalling litespeed and re-running the instance configuration, etc.

Haven't changed the SQL service account, and it doesnt matter who I run the restore command as (i.e. sa, my domain admin account, etc).