There can be reasons other than locking issues that cause this message. For example, if your table contains a Bit field which contains Nulls then it will cause problems in an Access linked table. I also recall reading that adding a Timestamp field can help out too.
Have you considered wrapping up your data access and editing in sprocs and disconnecting your FE? Many on this forum would advocate such an approach irrespective of the problems you are having. In that case at least you can handle concurrency issues within SQL Server (as well as further security benefits etc).