When you schedule a job to run from the server, the package is run under a different user context than when you run it manually. Check the network login that the SQL Server Agent service is running under, this login should have rights to read the MS Access database you are trying to pull in.
One way around this is to setup the Proxy account, however for more information on this problem check out the following article:
http://www.sqlservercentral.com/colu...iewingpack.asp
(SQL Server Central requires a free registration in order to view their articles but it's well worth the time it takes to register!)
Good luck!
Jeff