SQL Server 2000 SP4 problems with AWE
Looks to be a bit of a wild one.
SQL Server 2000 SP4 introduced a bug where only 1/2 the RAM can be accessed by SQL Server when AWE is enabled.
So, it you have 16GB, SQL Server will only use 8GB.
There is a Microsoft KB article # 899761 that describes the problem.
It's advice is to un-install SP4 and call PSS. A Hotfix for this is in progress.
The SP4 download site has now a warning about not installing SP4 on systems with AWE enabled. http://www.microsoft.com/sql/downloads/2000/sp4.asp
Now I wonder how SP4 got out the door with that problem!
Update 1: KB link is now available: http://support.microsoft.com/?kbid=899761
Update 2 (16 May): The hotfix is in testing, and a release is expected in about 7 days. For the moment, it will be a hotfix and not a SP re-release.