The PING might not be conclusive, and awful lot of routers and firewalls block ICMP packets, in which case PING won't work, but TCP/IP may work fine.
I'd echo checking what IP address your machine is using though. 169.x.x.x are the auto assigned addresses Windows uses when it can't get a DHCP allocated one, so if you have a auto-assigned address then it is likely that even if you can sign onto the wireless network, the DHCP server is ignoring you. This can be down to a few causes, but the most likely are (a) It has run out of leases or (b) It is using a MAC address white list, and yours ain't on there!