internet connection

[SansLogique]

Hi,
I'm completely in hell! I can't conect to the internet. My connection worked fine till last Monday BUT! I'm connected by wifi on the roof via router (static IP), there were problems, so I bought a new one. Now, my PC has an old XP installed and had a new Win 7. XP works still fine, W7 stopped working. After many attempts I reinstalled W7 (clean and formatted disk), but no luck. Even more strange is: I brought the PC to other house, just plugged the LAN cable (ADSL router connection) and everything worked just fine!
Everything on my PC is configured "Auto". I tried fixed IP adress, but the DHCP server of my router works just fine, this is not the problem.
When I try to fix it by Windows, it says "System is configured properly, but the device cannot connect to (www.microsoft.com)". Very useful advice!!!
Why it works with ADSL router, why it works with XP, but whatever I do, there is no internet connection with my wifi router here?
I can configure the router, router obviously works fine (no problem with XP), so no problem with drivers (the latest. of course), there is no problem with IP I got from router, no problem with MAC (I changed it, nothing happen), router is configured properly (it works with XP, even an old PC with Win 2000 works OK), so problem should be Win7. But why the Hell it worked with another ADSL router???
I have seen many solutions of "Win7 internet connection" problems, but nothing helped.
IP renew, DHCP flag, Bonjour, some Antivir, Firewalls, I know for sure, it is not my problem.
BUT what is?!?!

 

[Tometo]

Well make sure you reset your MAC address and than check the encryption you are using for the connection (if there is any) - I'm asuming your WiFi adapret is turned on Windows 7. Check if the Firewalls and the Antivir.

 

[SansLogique]

I had MAC adress filleed in my router settings. Then I deleted it - XP works in both ways. Win 7 in no way. I even changed the MAC adress, no luck. As for the FW and AV - without installed antivir and with FW turned off - no luck either. Not to mention with both ON it worked with the ADSL router.