Scalability Issue

We are attempting to perform scalability testing using the .NET Data Adapters and web client. We have built a Data Adapter that generates a push every 5 seconds of some data. The tests we have executed are shown in the table below. All but the first test of 10 users 50 Data Adapters failed with the a crash of the Data Adapters. The unique thing about the tests is that they all failed around the 175000 pushes. I should have noted that the Data Adapter pushes 180 times to the web client and the client has cells that increment a counter. So we would expect to see for each cell when the test is complete a count of 180. But as the load of users increases, the Total Pushes (users * Data Adapters * Finished count) reaches the 175000 mark and we loose a Data Adapter. It appears we are marginal on memory when we reach this level and have spread the Data Adapters across 5 hosts. So we had two questions:

1. Is there some limit using the evaluation license that would cause this?
2. Our web client connects to an engine with a different name for each client that we bring up. Could this be causing issues? Should we be using the same engine reference name for all clients?

Thanks in advance for your help.

Test Data:

Test Run 1
Users = 10
Data Dapters = 50
Finished Count = 180
Total # of Pushes = 90000

Test Run 2
Users = 20
Data Dapters = 50
Finished Count = 175
Total # of Pushes = 175000

Test Run 3
Users = 20
Data Dapters = 50
Finished Count = 175
Total # of Pushes = 175000

Test Run 4
Users = 30
Data Dapters = 50
Finished Count = 120
Total # of Pushes = 180000

Test Run 5
Users = 30
Data Dapters = 50
Finished Count = 120
Total # of Pushes = 180000

Test Run 6
Users = 60
Data Dapters = 50
Finished Count = 60
Total # of Pushes = 180000