Wifi connection has password issue with my Macbook Pro

I have a 2010 Macbook Pro (running Snow Leopard) and I connect to my home internet thru Wifi (via Thompson router).
The problem is, after I choose my Wifi from a list of Wifis and enter the password, majority of the times it fails to connect saying "Incorrect password", even though its correct. All I have to do is keep pressing the return key until a connection is established.
Very few times I get connected automatically without a need to enter the password and sometimes I get the connection on the first attempt, but usually it takes around 5-10 tries.
It doesn't happen to my Windows (vaio) laptop though. Anyone seen something likely and got it fixed?

Solution 1:

You could try 'Forget this network' in the Airport settings through System Preferences -> Network, then reconnect fresh again

Solution 2:

For others finding this thread because they too have the problem:

On my wife's MacBook Pro, the answer turned out to be that the laptop could not differentiate between the 2.4GHz and 5GHz version of the wireless, and if it connected to a different one than last time, told her the password was wrong. The cure was to 'split' the two wi-fi networks by adding '-5' to the 5GHz version SSID, then the Mac could tell them apart. It has the same passcode for both networks (although they could be different) and is now happy to connect to either, every time.

Why this suddenly crops up for some, is down to relative signal strength on each frequency, and maybe a new router having the 5GHz band for the first time, but with the same SSID. (That is how they are normally set up, but Apple has problems with that).

HTH someone.

Solution 3:

The problem was solved by a firmware update. It specifically addressed this password issue.