Did you know that you don't have to use your full post as the question title?
There are many, many, many reasons why data in your file might have the wrong data--even data from the same source duplicated over many records. Might have been a rogue script, replace field contents, an update type records import, might be a damaged file, though this is unlikely unless there are other issues.
By a "rogue script" I mean that a script was run at the wrong time, context or with wrong parameters and thus modified a lot of data in an incorrect manner.
Unless it repeats, you may never know as this could have just been user error.
To protect your data, there is no substitute for regular backups being made and then retained. If you have such back ups, you should be able to use them to restore this data. Sometimes checking back ups to find the newest one that doesn't have this wrong data provides a clue--at least a clue as to when it happened that might help you figure it out.
Thank you, philmodjunk. My experince with FileMaker is limited in the extreme. None of the factors you mentioned—rogue script . . . update type records import—am I familiar with. I will explore those further. In the meantime, the bottom line, I now see, is to keep backups. (Thanks also for your initial comment about the proper use of the question title.)
It is most likely not file corruption
We have seen this happen, when a user does a Replace, by mistake, on a Found set of Records ( was anyone working on those 200 records ? )
If you can upgrade to FileMaker 10 or higher, the Recover Utility now has a Log, so you can see if there are any "problems" in the file
> one of the text fields in each of about 200 of the 1,000+ records has been replaced with text that had existed in the same field in only one of the records.
My questions are: Has the file been corrupted?
Greg, I never knowingly executed a Replace, so perhaps it was user error. Thanks for your input and suggestion about upgrading. -- Jeff