Strange wireless problems.

I had a mate call me today and ask if I can look at his wireless network and in particular why he cannot print to the main computer. He has 3 machines, pC 1 has a Netgear wireless router and pc 2 and 3 have Netgear PCI wireless cards.
When you try and print on PC2 and choose the shared printer from PC1 although the print properties window appears nothing else happens. No error messages nothing. I noticed that he had no security setup so I setup WEP keys, SSID, and MAC addressess on the router and also on the 2 pci cards. PC3 had no problems but I seemed to have strange problems with PC2 as follows.
1.On reboot the Netgear config utility wont always start or will start but then shut down. Its still running according to the task manager but you cannot get it to open up so you can set the properties.
2. Under the page that scans for networks you cannot see Netgear even though you could before the security was set. But it still connected up for about 15 seconds and then disconnected again. Ive never seen this happen before. I double checked the Mac address was allowed for PC2 on the router which it was so why wouldnt it connect. PC 3 was set exactly the same on the routers MAc access list and it connecetd no problems.
I am also wondering if I am better off scrapping the Netgear config utility and using XPs own config utility instead? Any ideas as to what could be causing the strange problems? I ended up disabling MAC address filtering and PC2 now connects up again no problems.