AutoCAD Civil 3D :: Error / The Microsoft Jet Database Engine Cannot Open The File

We are using AutoCAD Civil 3D Land Desktop Companion 2009 on all machines and one of our machines is getting the message "Error opening Point Database" and then gives the project file pathcogopoints.mdb.

It also gives the message "The Microsoft Jet database engine cannot open the file.  It is already opened exclusively by another user, or you need permission to view its data."  It is not opened by another user and permissions have been given for all machines to access these files.

Background information:  We move older projects to an external hard drive for archiving and occasionally need to access them as the need arises.  We have done this successfully for some time without issue, but now one of our machines is giving the above error.  The other machine, which the external hard drive is connected, does not have this problem.  We tried moving one project file back to the original location and it seemed to work okay, but another file did not.  Some files were created using an older vrsion of AutoCAD, but that has not been a problem with opening them in the past.  All sharing permissions to the external hard drive have been checked and seem to be working properly.