Oppening old mdb file(Access 2000) with Access 2016 disables workings of Access 2000?

We installed new Access 2016, and we also still use old mdb files with Access 2000. Though old mdb files open in Access 2016, after using it, somehow Office re-configures itself to work with Access 2016 and then when I open the mdf file in the old Access 2000, some of the events like click fail with error message.

I am not sure how but, one of the technical people somehow restores the office to previous state, and then Access 2000 works as expected.

How can I resolve this conflict between two MS Office Installations?

If there is VBA code involved, opening an Access 2000 .mdb file will cause Microsoft to "helpfully" re-associate it with Access 2016 (or whatever version was used to open the .mdb file). In Access, click Tools, References, and check that the correct version of Microsoft Office Access Database Engine is selected.

Do you mean in

Access 2000 it should be Microsoft Access 9.0 Object Library

and in

Access 2016 it should be Microsoft Office Access 16.0 database engine object library

in VBA IDE?

The database engine and library (and any other references) need to match the version of Access that you are opening the.mdb file with.