iMac not connecting to wireless network

All of a sudden my imac of 2 months isn't connecting to my wireless network.
My macbook, iphone and apple tv are still connecting.

I'm running 10.6.4

Basically everytime I put my password in it says "connection failed" even though it is the right password.

I've tried changing my channel on the router and that didn't help.

Help

It sounds like a "keychain" error. Try this:

Open the "Keychain Access.app" from Applications -> Utilities. Look for the line that has your connection password and delete it. Before deleting it, make a copy and place it on your desktop.

Exit the Keychain Access application and restart your network router or modem. Try connecting again. You will have to enter a new password but this time it should work as it's supposed to.

Let us know. If that doesn't help, we can try something else.

Turns out I had to change the WPA to WEP and now it works.
Is this a known issue?
I would prefer to use a WPA but will have to make do for now.

Thanks for your help though.

No, that's not good. WPA is many times more secure than WEP which can be broken into very quickly.

I still think you had a keychain problem. Did you try what I suggested?