Belkin Surf N300 Wireless N Router F7D6301/ Ubuntu 11.04/ Lenovo Z575 - Not working

[SyncMr]

But I have already done the kernel upgrade. I thought of upgrading the kernel and giving it a try. After that when I logged into the older kernel version, my wireless popped up stating that wireless connection are available. I was able to connect successfully.

But the internet is very very slow. It is proceeding in bytes per second. And frequently am getting Problem loading page.

And I am still unable to log into the upgraded kernel. Wondering if I should remove the earlier kernel version as internet works fine here.

[fdrake]

i don't think the problem has nothing to do with the old kernel but you can try this
login into your old kernel and run

sudo aptitude purge linux-image-3.0-1-generic linux-headers-3 linux-image-3 
echo "deb http://archive.ubuntu.com/ubuntu natty-backports main universe multiverse restricted" |tee >> /etc/apt/sources.list
sudo aptitude update && sudo aptitude upgrade

then upgrade again the kernel to 3 if you wish. This time you should be able to login normally.

[SyncMr]

Now am not able to connect to internet. i.e.Am able to see the wireless connections. On giving connect, the wifi icon on the top right keeps connecting and prompts for password. I am giving the exact password but in vain. And not able to browse internet.

[fdrake]

Now am able to connect to internet. i.e.Am able to see the wireless connections. But not able to browse internet.

are you using the new kernel, right?
edit: i edited after seeing your edit... so there is a problem with the password. are you able to connect to an open network?
can you post the result for

nm-tool
sudo iwlist scan 
less /var/log/syslog | grep -i network | tail -100

also with a wire connection can you install the following package

sudo aptitude install wpasupplicant