Access Reporter makes good use of a new .NET technology called Remoting. Remoting permits 25 concurrent connections per CPU. If you need more than 25 concurrent connections, add another CPU!
Remoting requests are serviced by the .NET thread pool, which has a default limit of 25 threads per CPU. The CLR host is free to change the default value of 25, and managed code can also call out and change this value. The unmanaged interface ICorThreadPool has a method (CorGetMaxThreads) that can return the maximum size of the thread pool.
Check out Mike Woodring's page tools at www.bearcanyon.com is you are interested in calling this method and displaying the thread pool limit.