Windows 7: wifi no internet access with excellent signal

hi all, im having this weird problem for 5 days now, its really driving me crazy, so i have an alienware laptop, never had any problem before, this problem only happend about 5 days ago, everytime i start my laptop the network works fine, but after about 15 mins, the wifi automatically disconnects although the signal indicates excellent, i cannot browse internet or run anything that is connected to network, only by restarting my laptop can fix this; one thing funny about this is that if i open any sort of web page before this problem occurs, i can still browse that certain web page even after this problem occurs; ive tried to flush dns, reset net interface, obtain ip address manually, none of them worked, so here im hoping that somebody on this forum can help me out.

I would think about resetting the router if you haven't done so already. After resetting the router go through the wireless settings again, set your SSID, password and also use WPA2 security with AES encryption.