Q I bought two Belkin F5D7000 PCI wireless cards, one for use with a Dell Dimension E500 and one for use with an RM Nimbus. The RM is running Xubuntu 8.04 and the Dell Dimension is running Xubuntu 8.10. I installed them both using NdisWrapper and am able to connect to my wireless network absolutely fine on the RM. The Dell connected the first time I tried, but once I had rebooted - even though I could see the list of networks within range - I was unable to connect. I disabled WEP security on the router and configured access control instead and was then able to connect again, but only once. Upon reboot, the list of networks was there, but again I was unable to connect. I then disabled access control and again was able to connect once, but never after that.
I suspected it might a problem with the card, so I swapped it for the one in the RM. Again, I could connect once, but when I rebooted I faced the same problem. Both cards work absolutely fine in the other machine. I'm out of ideas now - I can't fathom why it'll only work once!
A The use of NdisWrapper with the newer Ubuntu appears to be the cause of your problems. NdisWrapper should only be used as a last resort when there's no native driver. Aside from the security implications of running closed-source Windows code as root, which is scary enough in itself, there is the possibility of a clash with the native driver. That appears to be the case here, as the RTL8180 driver now supports these cards and this driver has been improved of late, increasing the hardware it supports. Xubuntu 8.10 has a more recent set of kernel modules, so it's likely that this module is being automatically loaded when you boot, locking out NdisWrapper. When you go through the manual configuration, you are somehow overriding this, so the NdisWrapper driver works - at least until you reboot.
The solution is simple and an improvement on your current setup. Remove NdisWrapper and switch to the in-kernel RTL8180 driver. You should find that removing NdisWrapper and rebooting is enough to enable the kernel driver to work; if not, try loading it manually with
sudo modprobe -v rtl8180
If that works, you can have the module loaded automatically at boot by adding rtl8180 to the end of the file /etc/modules, which lists modules to be loaded when you boot.
By the way, the RTL8180 driver supports WPA encryption, which is far superior to the security provided by WEP (although a wet paper bag is more secure than WEP). If your router supports it, you should switch over to WPA or WPA2, which is an easy task in Gnome's NetworkManager.