Limited Connectivity and No Internet Connection

Hi,
I have a Toshiba laptop, specs are as follows:
Processor: T2400@ 1.83GHz 1.83 GHz.
Installed Memory (RAM) : 2.5 GB.
System Type: 32 Bit Operating System.
No pen or touch input is available on display.
I am using Windows 7 Professional.
I don't know the root of the problem, but every time I try to connect to our wireless internet, I will be getting a message that I have LIMITED CONNECTIVITY and/or NO INTERNET ACCESS. I already tried to download the latest version of the wireless driver ,but that does not solve the problem.
I was thinking maybe the Ethernet card is defective. But when I try to use cable and connect it directly to the router internet is OK and works alright. And it is also important to note that other pc/laptops are able to connect with this router with no problem at all.
What causes this problem and how do I solve this?
Thank you.
