Where is your problem description located?
Anyway, PS is using UDP, not TCP, but they\'ll be in the same stack anyway, just so you don\'t look for the wrong thing. I\'m going to refer to it as \"IP stack\" from now on.
The IP stack will be installed with the first network stuff. What OS are you using, anyway?
AFAICS, the only way of checking the IP stack of your machine is to try a different OS on this machine, or a different machine, all with the exact same settings.
Alternatively, you can use a protocol analyzer on the net connection, which, however, requires some knowledge on the protocols.
Also, you could write a program that uses the stack extensively so you can see if it fails on that machine and how.
Furthermore, you could run the PS server on another machine in your network and try if you can work with it. If it works, then the stack is OK and your problem lies elsewhere. Using the local machine would also be possible (localhost), though it will not show issues that come with packet loss or latency, so it may fail to show a problem.
If the local network passes, then you can slow it down by causing heavy traffic to the client and server machines.
If all of that works, your stack most likely is OK. If not, there might be a problem, but I\'d look for it in the driver for the network card or modem / whatever you\'re having, or maybe the hardware itself, since the only way of the stack being broken but somehow working would be to mangle the libraries somehow, without destroying them. Current OSes should have working stacks, since UDP/IP has been arounf for ages.