If your problem is like mine, you are getting this error because your MDAC got hosed.
I was un-installing something seemingly harmless and before I knew it I saw a flurry of mdac dlls being deleted.
After that, SQLServer7's Enterprise Manager and other VB6 database apps started failing with this error.
I re-installed the MDAC (26) and it (thankfully) fixed the problem.
Hope this helps.