Question:

I'm receiving "HTTP Error 500.13 - Server error: Web server is too busy" intermittently on some of my ASP pages.

Answer:

If you're using MS Access as a database back end, then this is likely the cause of your problem. 

While MS Access databases CAN work in this type of solution, they are the least preferred method.  There is no "MS Access engine" running on the server that is designed to manage multiple concurrent requests for the same resource (record/file), you simply have ASP with a driver with instructions on how to access the MDB file and file format (I'm simplifying, but for comparison sake).  With an MSSQL or MySQL database backend, you have a database engine/server that is designed to manage concurrent connections and conflicts through caching and other forms of process/thread management. 

If you google/yahoo this error and MS Access (or .mdb), you'll find a lot of discussion on this topic... and although there are some differening points of view, but the vast majority agree with the description provided above, and the solution is to move to an appropriate database backend capable of managing concurrent connections in a more efficient manner.   You should migrate your application to utilize MySQL or MSSQL as the database back end.   Most of our hosting plans already include MySQL databases and some include MSSQL.  Check your LIMITS in the control panel, or submit a request to Support if you need clarification or are interested in upgrading to a plan that includes MySQL or MSSQL databases.

Note that this is a different condition than what is described here:

ERROR: Server Error in '/' Application - Server Too Busy