D-Link Rangebooster N issues

I recently had to replace my NIC and Router. My router is a D-Link DIR-625 RangeBooster N, and the card is a D-Link DWA-542 RangeBooster N. The network setup is a wired desktop, wireless laptop, and wireless desktop (Windows XP, SP2, where the new NIC was installed).

After installing the card, it held a connection, albeit a weak one. While setting up, I looked over various networking sites and forums, and was told that setting the wireless connections to the following was the way to go to get rid of an irritating message I was having (No certificate, but connected to the network fine):

Network Authentication: WPA-SPK
Data Encryption: AES

Having worked with the laptop, I tried doing the same thing with the desktop, with the new NIC. After the first install, I was able to get a weak connection temporarily. After a reset of the computer, it couldn't connect to the network at all, so I reinstalled the card, which worked for the better part of a day. Towards the end of the day, the connection gave out. Now, on the network properties section, the network doesn't have the authentication options of WPA or WPA-PSK, and the card can't detect any networks in range, although there's always been a few (only one ours, the rest neighbour's).

Also, when going into the wireless connection properties, Wireless Networks tabs, the "Use Windows to configure my wireless network settings" checkbox is always unchecked, despite repeatedly checking it.

I've tried the program that came with the NIC, and it's never gotten anywhere close to where the Windows one has.

What's the problem here, and how can I fix it?