I just installed Direct Oracle Access for Delphi 4. The setup procedure worked just fine, but when I restarted Delphi I got the following error message:

Can't load package C:\Program Files\Borland\Delphi4\lib\doa.bpl.
A device attached to the system is not functioning.

What's wrong?

This problem is most likely caused by Update Pack incompatibility in Delphi 4. Direct Oracle Access for Delphi 4 requires that you have at least Update Pack 2 installed, which is available on the Borland web site:

http://www.borland.com/devsupport/delphi/downloads