You either do not have enough signal or you have interference.
You need to try the standard change the channel on the router trick and see if it makes any difference. You could have a neighbor that turned on a new router and if you and him use a common SSID you will stop all over each other.
You next thing to try is to buy a cheap USB wireless card. It is very common for the built in cards to fail over time. As long as it works at all the vendor will say its fine.
Your last thing would be the router but before you replace that you may want to try borrow another pc to see if they both have problems.
Hard to say lots and lots of things cause this symptom
I have a Gateway laptop and i used to leave it in my bedroom and then all of a sudden i started to get problems where i would randomly disconnect then reconnect again, i never thought of it much until i completely stopped being able to connect to my internet from my bedroom and other rooms.
The only way i can connect to my internet is if i am right beside my router in the same room, if i am on the other side of the wall where my living room is (still beside the router with a wall between) i barely get an internet connection.
I sent my computer into Future Shop and sent it back to Gateway and they found nothing wrong.
PLEASE HELP.
PS. I am running on Windows 7 64 Bit and I have a Rogers SMC Networks router.

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