If you have internet via your cable tv line:
Try connecting your PC directly to the cable modem.
Unplug the cable from your router that connects to your PC.
Then unplug the cable from your cable modem, that connects to your router.
Then connect it directly to the Cable Modem.
(So basically, you are connecting your PC directly to your cable modem, bypassing your router.)
Now unplug the power from your modem for 1 minute. Then plug it back it and let it power up.
Now check to see if your internet works. If so, launch Aces High and see if problem still exists.
If your internet does not work, try restarting your computer, then launch AH and check for problem.
If problem goes away, I'll provide more details to work on your router.
Also, you still have Service Pack 2 for windows XP. You might want to upgrade to SP3 afterwards.