Start by downloading one of the Philips example/demo configurations to your Prontos. If these cause freezing, then there is something wrong with your PC/Prontos. If, however, they run ok then this strongly suggests that your configuration is the problem.

Then run the configuration in the simulator. If ok, this might suggest that there is something wrong with with the way you have set up your networking (e.g. both Prontos using the same IP address). If not ok, then do the debugging using the simulator.

Do you use scripts? If so, did you write them yourself? Infinite loops can effectively only occur in a script.

Do you use extenders? If so, do they ever work?