wifi shield arduino version

I jsut found out after a view hours of work that with arduino 1.0.5 the wifi shield is not working. it will connect to the network but no sockets availeble at all. after using 1.0.4 again, it works fine immediatly.
Doe's anybody know what the problem with the 1.0.5 is?

looking at the 1.0.5 changelog there were "Upgrades to WiFi library" and "Upgrades to WiFi firmwares", although i can't find what that actually was on github

I just did a couple tests and I will take a guess that you have a mismatch between the WiFi library in the Arduino application and the firmware running on the shield.

I have two WiFi shields, one with it’s original firmware and the other re-flashed with the latest firmware. The early firmware works with applications compiled with Arduino 1.0.4. The later firmware works with (the same) applications compiled with Arduino 1.0.5. But never the twain shall meet! Early firmware and Arduino 1.0.5 causes the shield to send a TCP ReSeT in reply to a TCP SYNchronise, effectively denying the connection request.

So, if you are using Arduino 1.0.5, the shield needs to be running (at least) the firmware which ships inside the Hardware folder. To check which firmware version is running on the shield, use
Serial.print(WiFi.firmwareVersion);
If it returned < 1.1 you probably need to reflash to use Arduino 1.0.5 …And good luck with that.