Wifi problem, and how to choose between Wifi/GPRS?

Hi!
This monday I received my M8 :D
I installed last firmware, 0.9.2.6 SE... everything ok, but I have problems with Wifi connection.
Opera or any aplication that require Internet connection doesn't work with Wifi, but work perfectly with GPRS.
I have installed the last version of M8Cracker and M8Sprite... I've found and configured my Wifi AP, but it still not working, and I don't know if the cause is that Wifi doesn't work or I have a bad configuration.
I see that Opera works if I have GPRS enabled, but if I disable GPRS Opera show the next message: "Network link not exist, please open setting!".
Anybody has the same problem?
And, another question...there are the possibility of choose if I want that Opera (or another internet aplication) works only with Wifi, indepently of GPRS is enabled?
Sorry for my bad english (i'm Spanish) and thanks!

Opera works with the connection it founds, wifi or gprs. If you have just a wifi connection opera will works with it.

About the wifi, is it an open wifi? wep? wpa? Try different wifi lines, if it doesnt work with two different open wifi lines, then there is a problem.

Thanks for the reply!
Then, in the case of Wifi and GPRS are enabled, Wifi has any type of priority?
The Wifi AP I tested it's from my house, and it's WEP protected. I tried to change the type of connection to Closed, Manual or Auto, but it didn't work.
This afternoon I will try in another Wifi AP

you have to use closed

auto and manual is for proxy-use

Problem solved; I tried to connect to Wifi in my brother's house and works really good
I will try to reconfigure my router
Thanks for the help!

I am having trouble with getting WiFi to work after having used M8cracker to enable it. I have tried using it with the default browser in firmware version 0.9.6.9 in areas where there is public open WiFi available, like railway stations for instance, but I have only been able to get it to work once after much effort. I try fiddling with settings like fixed IP address and restarting, but all I get is the message "Network link not exist, please open setting!". Sometimes I do not even get this message. On the one occassion I did get it to work in a car ferry the browser opened a page where I could input the user name and password supplied to me by the ferry people.

I have no idea what open Wifi, WPA or WEp means, or if they are relevant when using open public WiFi.