BO says this:
For Windows 98 and NT4:
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1. In the appropriate path, check if the required DLLs are present:
a) In path "files\common files\microsoft shared\dao": dao350.dll
b) In path "winnt\ system32": ExpSrv.dll, MSExcl35.dll, MSJet35.dll, MSJInt35.dll, MSJtEr35.dll, MSRepl35.dll, MSRD2x35.dll, VBAJet32.dll, msexch35.dll, MStext35.dll
2. Check the versions of these files against a machine not experiencing this issue. Copy any missing or older DLLs from this machine.
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Re-Install the Microsoft Data Access Pack from BusinessObjects 5.1 Disk 1
At the message asking to prompt if newer DLLs exist on the system, do not select the box but close the window. BusinessObjects will not overwrite newer DLLs, and will only add the needed files into the system.
1. Select \Vol1\Microsoft\Dataac2. Run Dataac.exe.
3. Select Data Access Pack and install.
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Install the Microsoft Data Access Pack "Jet35sp3.exe" directly from the Microsoft support website.
But there are many other possibilities for this error, and I'm not sure BO will be happy if they notice I copy/paste info from their Knowledge Base (support contract!)