No laptop connection

[#1]

Not very good at explaining tech stuff so please bear with me.
Both desktop and laptop were connected via router. Desktop still
connected but lost laptop connection and keep getting following error
message ' windows association failed because windows didn't receive any
response from the wireless router or access point'.
The thing is i was able to temporarily use an unsecured network before
being booted off and wonder why i could do so whilst not being able to
use my network.
Never had this problem before and router is new(3 weeks) and i guess ok
because i have a connection via desktop.

> Am using Vista basic


Now there is a yellow exclamation mark next to my network's name in the connection list.    Signal strength for it is listed as excellent .

[#2]

Given that it used to work: either the wireless in your router has developed a fault or the wireless adaptor in your laptop has developed a fault or something has come along in your neighbourhood that is causing a lot of interference with the wireless signal.  I guess the thing to try first is to log on to your router (from the desktop), change the wireless channel and see if that improves things.