Ports are getting stuck using DigiNeo8 - very argent

One of our customers is using Digi Neo8. the problem is as follows:

They are using a software program that use 8 COMM Port for transferring transactions.

The problem is that the ports get stuck when trying to execute the transaction.
When trying to test the stuck port using hyper terminal, the port is still stuck.

Is there any setting that should be made with the Digi driver to release the port?

Appreciate your answer
Sarit