wireless internet connection issues with iMac

Hi everyone, hopefully someone can help me solve a problem. I am new to the mac world, but got a 21.5" iMac the other day. I can connect it to the internet just fine, but every now and then (sometimes just 30 seconds after I re-connected) it decides it doesn't want to be connected anymore. When I click on the airport wifi thing on the top right, it says I am still connected. So to reconnect I have been turning airport off and then back on, and it will connect no problem, just to cut out again. Is this the iMac problem, or is this a problem with my internet service or is this a modem/wireless router problem? My brother in law has a mac book pro which has similar problems. We have AT&T DSL (which sucks) and a 2wire modem/router.

Thank you!!

Moved to correct forum.

Welcome to the Mac Forums. Since your iMac is new, we can probably eliminate any hardware glitches and focus in on your connection. It sounds like it could be a problem with the router (location, signal strength) or perhaps with encryption of the wireless signal.

Which method of encryption are you using? If it's WEP, that could be your problem. WEP is not only insecure, it's also unstable. If you are using WEP, I suggest changing it to WPA2 and use a strong pass phrase.

To chime in, depending on which wireless router and router placement you have, it could also be interference from other appliances, (microwave, phones, etc), in the household. I would start with the security suggestions above and also make sure other appliances are not interfering with the signal.

Sorry to be a party-pooper but I think it could be a hardware problem.
I had exactly the same experience but had no problem with a PC or my MacBook Pro. Ended up taking the brand new iMac back for a refund. A great disappointment as I was looking forward to my new machine.
A search will reveal it is a common problem.