Data source name not found and no default driver specified

I have created an exe that uses an Access database on a CD as a data source.
Obviously, we can't be sure we can create a DSN on the user's machine, so we
use a DSN'less connection. The CD was released almost two years ago, but
now I have a user reporting that the database gives this error when the
program attempts to retrieve records:

[Microsoft][ODBC Driver Manager] Data source name not found and no default
driver specified

I'm not sure what to make of this, since I'm not using a DSN. I had her
download the MDAC Component Checker, and she reports her version info as

MDAC 2.7 SP1 on windows XP SP1

Has anyone seen anything like this before?

Thanks;

Amy