Q: my mac mini won't stay connected with wi-fi

There are any number of possibilities, including the "cable people's" modem/router. Just becuse it works with their PC does not necessarily mean it is compatible with your Mac mini. Do you, or a friend, have another Apple device you can access the WiFi network with, such as an iPhone, iPad, or even an iPod? If another Apple device fails it is time to call the "cable people" back for another try. I went through three cable modems in the space of a month before my provider got it right.

Otherwise take the Mac mini to the Genius Desk at the nearest Apple Store -- be sure and call ahead for an appointment or risk a wait of several hours -- and have them check it out there. If there is a hardwar problem you are going to end up thre anyway so why not start there in the first place?

Hello, some good advice from joe, but another thing to try...

Make a New Location, Using network locations in Mac OS X ...

http://support.apple.com/kb/HT2712

10.5, 10.6, 10.7 & 10.8…

System Preferences>Network, top of window>Locations>Edit Locations, little plus icon, give it a name.

10.5.x/10.6.x/10.7.x/10.8.x instructions...

System Preferences>Network, click on the little gear at the bottom next to the + & - icons, (unlock lock first if locked), choose Set Service Order.

The interface that connects to the Internet should be dragged to the top of the list.

If using Wifi/Airport...

Instead of joining your Network from the list, click the WiFi icon at the top, and click join other network. Fill in everything as needed.

For 10.5/10.6/10.7/10.8, System Preferences>Network, unlock the lock if need be, highlight the Interface you use to connect to Internet, click on the advanced button, click on the DNS tab, click on the little plus icon, then add these numbers...

208.67.222.222

208.67.220.220

(There may be better or faster DNS numbers in your area, but these should be a good test).

Click OK.

If that doesn't work try changing channels on your Router.