Locks in a logged database

I am converting my OnLine databases and applications to buffered logging and I am having problems with the system tables being locked. If I have one session in a transaction updating a table and a second session attempts read data from the table (or attempting to select count(*) from the table the second session it told it cannot access system tables, 107 isam error. I can get round this by waiting until the lock is release (not really a practical solution) or changing the isolation level to dirty read when reading the table. Am I getting it all wrong ? Is OnLine just configured wrong or is this just the way it works ? Thanks in advance -- Fergus Hayne