Please solve my problem in network connectivity

Hello,
I have a (hopefully) small problem. Our house subscribes to DSL. My computer - the one experiencing the problem - experiences short lapses in connectivity. For 1 to 2 seconds, out of 30 to 60 seconds, a message will pop up indicating that the computer has limited or no connectivity and then the computer will immediately reconnect itself. It seems to repeat in a continuous cycle always timed in these 30 to 60 second intervals. This may be the cause of problems with my daughter's notebook which is on this network wirelessly. I was wondering if anyone had experienced this problem before and had a solution or at least some ideas on different things to try. Thanks in advance for your help and suggesstions.