Verify you drivers are current.
Check for a firmware upgrade on the router (Do it carefully).

Check you have DHCP enabled on the router, and on the laptop.

If the problems continue.

1). uninstall the driver from the laptop and reinstall.

Still no good ??
2)Contact Cisco support.
I had a D-link setup that did a similiar thing.
They gave me a parameter change that cured it for a while.
I don't remember what the parm was.

Oh also try set the router to only connect at ?? speed and set the card the same. thats another idea.

__________________
KLK, MCSE

1990 500SL

I was always taught to respect my elders.
I don't have to respect too many people anymore.