Visio Object/Preview Problem

I am currently running Visio 2000 on two platforms (WIN 95 and WIn 98SE). Recently when I save a Visio diagram, it does not save a "preview" of the diagram that is displayed when I go to the "open" command and browse the diagram files, despite the "preview" button of "first page" being checked in either "draft" or "detailed" quality.
In addition, when I import the same diagram into Word, the diagram does not show up in the document. It is there when I double-click to edit it, but either shows no diagram or, in a few cases, shows a corner of the diagram greatly enlarged. Completely removing Visio (including registry deletions as per Microsoft) and reinstalling did not solve the problem.