Here's how we fixed this problem - had the same problem -just got off the phone with Microsoft. Here's how you fix it:
Go to your SQL Server CD, go to the x86\repostry folder...copy the following files to the Program Files\Microsoft Shared\Repostry folder on your SQL Server
insrepim.dll
InsRepIM.exe
msmdcxml.dll
repbr.dll
sqlmmcrp.chm
go to the x86\repostry\res\1033 folder on the cd
copy the following files to Program Files\Microsoft Shared\Repostry\Resources\1033
msmdcxml.rll
msrmirc.rll
repbrmdc.rll
repbrui.rll
next, go to your sql2ksp3 folder on your server (this is where you installed sp3a from) go to the x86\repostry folder
copy the following files to Program Files\Microsoft Shared\Repostry on your SQL box
dbscan.dll
repbrui.dll
repodbc.dll
next go to x86\repostry\res\1033 (again from the service pack setup) copy the following files to Program Files\Microsoft Shared\Repostry\Resources\1033
reprc.rll
Finally, run the following script:
regsvr32 "C:\Program Files\Common Files\Microsoft Shared\Repostry\dbscan.dll"
regsvr32 "C:\Program Files\Common Files\Microsoft Shared\Repostry\insrepim.dll"
regsvr32 "C:\Program Files\Common Files\Microsoft Shared\Repostry\msmdcxml.dll"
regsvr32 "C:\Program Files\Common Files\Microsoft Shared\Repostry\repbr.dll"
regsvr32 "C:\Program Files\Common Files\Microsoft Shared\Repostry\repodbc.dll"
regsvr32 "C:\Program Files\Common Files\Microsoft Shared\Repostry\repbrui.dll"
Now go into Enterprise Manager - the error should be gone. Good Luck!!