Record Locking Access97 Front End to SQL

What is the default recordlocking method used by Access97? Using Access97 as a front end to SQL Server 2000, record locks taking place in SQL Server preventing users from logging on and modifying records. The question is why does this happen when using Access 97 as front end. Access97 tables are linked via ODBC system DSNs to SQL Server Back end. Thanks for your help.