Improperly uninstalling SQL 7.0, from SBS 4.5, may break the Content Index Service, and may generate the following error:
The Dynamic Link library Query.dll could not be found in the specified path.
The uninstall of SQL 7.0 deletes the Qperf.dll and Query.dll files.
Before uninstalling SQL 7.0, use Regedt32 to navigate to:
If the data value for Qperf.dll is 1, set it to 2. If the data value for Query.dll is 1, set it to 2.
To resolve your problem, very/set the entries above and place the missing files in the C:\Winnt.sbs\System32 folder.
You can extract them from the Is20.cab at CD-ROM #2:\Ntoptpak\En\x86\Winnt.srv\.