I found this procedure from another site. It should fix the problems you are seeing with your D-link DWA552 adaptor.
FIXED: Solution follows.
1. download newest drivers
for windows 7 here: Latest Atheros WLAN drivers for Windows 7 and Vista (x86 & x64) - LaptopVideo2Go Forums
2. Go to the control panel and uninstall any dlink install.
3. Go to the control panel -> hardware and sound -> Device Manager and click on "network adapters" then find if any wireless adapter is installed; if so uninstall it. Now right click in the device manager window and select "scan for new hardware". A new device should be found by windows. If it is UNABLE to install a device, then you may proceed to reboot your pc, otherwise continue to uninstall AND check the delete driver
also button and looking for new hardware until windows CANNOT install the found hardware.
4. After rebooting your pc, extract the new drivers to a folder, then go to device manager again and select the found network device. Right click it and selct update driver. Chose to install from pc, and select the folder with the driver in it and let it install.
5. After the install reboot your pc.
If it still does not connect properly do the following.
go to your router set up and select the following settings in the wireless connection settings.
- encryption type: WPA or WPA2 automatic
- Wireless mode: b,g or n automatic (just n should be ok as well)
- frequency: 20/40hz automatic
- in your adapter's settings, enable wireless-n adhoc
This should fix the issue with intermittent drops, not being able to find the network etc. It seems that in Win 7 the new drivers do not work very well with wireless g on this card as testing showed the same issues when switching from n, or mixed to just g.