As long as they are both trying to work with the same Access database and both are using the same Excel file, I'm going to guess one of them does not have the location of either the db or Excel file set as a trusted location.
If it happened on both (or if the workbook files are not the same) I'd say one of the workbooks has a space in front of one of the column headers. Probably not real noticeable in Excel, but Access will choke on it with this error number as the result.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.