wireless connection won't stay connected

My wireless internet connection goes from connected with an excellent signal
strength for approx. 10 seconds to no signal strength for approx another 10
seconds. It will reconnect to either excellent, or low, or very good
strength for only another 10 seconds. It just seems that for some reason the
signal is being interrupted or something is not right with the built in
wireless card. We have 3 other laptops connected to the wireless and they
all work fine. Up until yesterday I have had no problems with connectivity.
I have tried the repair several times and it does not solve the problem. I
have even done a system restore and still the problem exists. Can someone
help???