Catastrophic Error.

Hi. I've Windows 2000 Advanced Server with Service Pack4. Sql-Enterprise with Service pack3.
There's a strange error when i try to open a table for records through Enterprise-Manager; it says "Catastrophic Error" and some times it says "Class not registered". However Query-Analyzer works fine. I can't connect through any Client-Server application to any database, same error.
I've reinstalled SQL thrice but the same problem. Please suggest if any one has faced this problem.
Regards.Its problem with the client tools installed on the machine and never use EM tool to return the records, QA is the best bet.

Replace the client tools alongwith service pack to get rid of the issue.|||Thanx for ur kind response, Satya. As i mentioned; i've tried reinstalling SQL. If i remove the database and reinstall only the client tools, the same problem persists. Neither i can connect through any Client-Server application with or without the client tools. I need to reinstall the operating-sys i guess.
Regards.|||Before going for big-shot lets go this way :
Uninstall client tools and remove all SQL referenced registry keys then reboot.

Perform fresh install from another CD (if avilable) and see the results.

If the problem persists then think about replacing the OS files and I'm sure this is something to do with SQL tools only in some sort of mis-match of DLLs.

BTW,|||Same error; "class not registered". However i am greatful to u for ur kind replies. How do i replace the operating system files; by choosing the "repair" option while installation of operating-system?|||Yes|||I have the exact same problem, did you get a solution for this?|||I have also heard of this but have not had the problem. Is it the case that the OS was installed and patched to SP4 before installing SQL? I think that's the cause, but it's only a theory. Maybe this order is better:

O/S to SP3
SQL to SP3a
O/S to SP4

?

OSCI|||In my case I use windows 2003 server (standard) then SQL 2000 and sp3.
I tried to reinstall everything except the OS..