Performance Issues

Hello, I have an interesting issue. I am running Axapta 3.0 SP3 o(SQL 2000)n an HP Proliant w/5.5GB RAM running RAID-1 for the boot volume and RAID-5 for the DATA volumes. My transaction log lives on the boot volume. We are seeing sporadic performance issues…In our tier-2 environment with about 20 or so users…things will run great for 1 or 2 days…then there seems to be a lot of action on SQL and the CPU is up to 30-50% utilization. I have done some homework and I see that there is one user with about 10spid’s open with exclusive locks on tempdb. This doesn’t seem right…I am not sure why this is happening…normally it looks like all of the users have S (shared) locks going…but in this case…this one user…seems to create 10 or so X (exclusive locks) on tembdb…not on our main database. Does anyone have any insight into why this may be happening… The issue we are seeing is some heavy action on SQL and a ton of escalating locks on our main database…which (of course) makes things very slow for the users… Any insight would be appreciated…