Cognos Impromptu with multiple versions of Oracle client

[thecomputerguy74]

We are running two versions of the Oracle client on Windows XP machines (9i and 11g), and we are expecting Cognos Impromptu to use 11g, as it does on the many others, but for some reason, on a few it defaults to using 9i.  Is there some way we can force Impromptu to use a specific client?  I've been through all of the ini files and the registry, and can't seem to find anything. 

The reason we have two Oracle clients installed is because we have other software that won't use anything above 9i, but we need to use Oracle 11g for Impromptu, for internal reasons.  Removing either version is not an option.  The very large majority of users have this working without issue.

Thank you in advance for any help you may have.

Robert