Hello Beth,
Probably thought of this yourselve, but why not test the link on a small table. If the result is negative, you can rule out the idea that he file-size is the problem.
When you link the table, be sure to define a unique key (on one or a combination of fields) to get proper read-out through ODBC.
Running some queries from Access can cause you to believe that nothing is happening (large table-scans, for instance) and Access does not seem to respond anymore. In the background the query is probably still running.
In general, it depends more on the type of query you define on a linked table than the size of the file you are addressing.