use windows to configure my wireless settings

[learntojive]

I have Sky for my broadband, I was on the phone to their technical people last week with a problem and she altered a few numbers and settings and reset the router.
The laptop we use works fine but the desktop upstairs which has a wireless adapter now won't connect unless I go in each time and tick the box "use windows to configure my wireless settings" and then it connects straight away. From what I have read this box should remain ticked by default but it clears when the computer is turbed off.
Nothing has changed at my end , it didn't do this before and always connected without any problems.
I have rung them back twice but they tell me it has nothing to do with the broadband and must be the settings on my wireless adapter. I've looked at them but daren't change any of the settings in case I muck it up, when I tick this box it does work fine but it's just odd because I never had to do this before. Does anyone know what has gone wrong and if this is easily rectified? Thanks in advance for any help :o)