LSASS.exe taking over CPU on incremental update (FT-Catalog)

Hello everyone,
I've managed to get FT-Population running after being at war with a changed user-account of mssql service (switched both back to localsystem, now the population works fine).
But if i want to do an incremental update, LSASS.EXE takes over CPU (as much as it gets) and my SQL is not available for any other queries.

I've tried this on similar tables with less records, but the error is the same (none, peaking cpu until completion).
The main problem is that the big table seems to take ~3-5 hours for an incremental update, and i cannot have the system running 100% (on 4 cpus) at this time...

System information:
Microsoft SQL Server 2000 - 8.00.194 (Intel X86) Aug 6 2000 00:57:48 Copyright (c) 1988-2000 on Windows NT 5.0 (Build 2195: Service Pack 4)

CPU: 4x CPU (don't know the clock)
Memory: 1.5 G

I have browsed newsgroups and other forums for a solution, but couldn't find any answer.
I've checked the service trough TokenMon and FileMon (sysinternals) but couldnt find any errors...

I would really appreciate any help!!

Thank you for every post!no one?|||This sounds like a fairly obvious and severe infinite-loop problem that surely must have been reported on Microsoft's support-site, and possibly fixed there. This sounds like a pretty severe "fire" and you can't possibly be the first one to have smelled that smoke.|||i've searched newsposts, kb's - found nothing... nothing with the exact same error, but in combination with other services...|||found it!

- rename main admin account back to main setting (administrator)
- re-install sp3a (sql)

now it works fine! :D