Does Scroll Wheel Malfunction Mean Corrupt Data?

Hi,

I'm using a commercial Filemaker Pro database called Ebase (version 1) along with FMP 5 for Windows 98. Last week the database crashed because of a virus and I replaced the entire database (all primary and related files) with a backup copy. The new version appears fine, except the scroll wheels on both computers' mice no longer scroll between records. We're still able to move between records using the scroll icon at upper left, but I'm worried that the change signals a bigger problem.

Here's what I've done to troubleshoot:

- Ensured that we're viewing the data in "form" mode

- Imported all the data into a "clean" empty backup copy of the database (the problem recurred in the new copy)

- Begun deleting all data from the above copy - at which point I got a message saying something like "not all records were distinct and those that weren't couldn't be deleted."

I'm thinking I've got corrupt data now - does that sound right? If so, what do I do? How do I isolate the corrupt records, given that they're functioning normally, and their related records? Can corrupt records be fixed? Am I barking up the right tree at all?

(Furthermore - those records I began deleting (then canceled by hitting Escape) are still there. Are they intact, or do I need to replace that data with a clean copy?)