I just had to install the original drivers and it worked somehow. (But not really good...)
Maybe you have to configure the networksettings on your pc to get it working properly.
In the time I used my Z with xp I had to reinstall the drivers 4 or more times because winXP didn't recognize the Z anymore. Also I wasn't able to connect to my local network unless I installed a bridge between my network-card and my Z.
Then I had internet for my Z, but not for my pc, really weird...
I hope it helped you although I don't think so...