I am experiencing a similar error, also when two tables are joined. My tables are in EXCEL, the first one being about 19K rows and the second about 23K rows.
The error occurs in the Microsoft JET layer and is not typically a setting that Tableau can control. We have seen this error occur when more than 255 columns are returned in a query as well as when a text field exceeds 255 characters or contains invalid characters for the data type - which may be the case here.
Hopefully this provides some insight!
Thanks, Tracy. I will cut down the fields then.