Laptop won't connect to network when first turned on?

[Rockstar]

I have a Dell Inspiron that is only about 4 months old. I use a Linksys router for my wireless network at home. When I first had this laptop, It would connect to the network automatically when I turned it on. For the past month, every time I turn it on, it either connects to the network but with no internet connect, or it just doesn't connect at all. To make it connect, I either have to manually disconnect it from the network through my network settings and then connect it again, or I have to choose repair, and then have it get a new ip address. What can I do?

[addit420]

Check for any manual over ride settings for the wireless adapter. You may have disabled/enabled the DHCP server.