Wifi Keeps Timing Out

For almost a month now, my wifi randomly stops working and stays down for almost 24 hours every week. I get connection timeouts if I attempt to get back on the network. I never changed anything, it just started. Literally nothing I do works, it just boots me off and then let me back on when it wants. From restarting the modem, to playing with the settings from location to resetting the DHCP, nothing works. I've even removed the password from keychain and re-added, nothing. Kicks me off randomly, and lets me back on within 24 hours whenever it pleases. So when I say that nothing works, I mean NOTHING works. It's on a timer of sorts. I don't plan on dealing with this every week, seriously. And I'm on Mountain Lion, where I've read things saying that making a custom location and a manual hardware number fixes it, but it doesn't. It's like it's on a bewitched schedule, where it turns itself off weekly for around 16 hours and is completely immune to anything that helps it (even diagnostics fails).

I have a Linksys router, and no, this does not happen on any other device in the house. Just on my iMac, and nothing else at all. I've even changed the channels on the router, nothing.

If I don't get help on here (most of my threads get ignored usually) and this continues to happen, I'm going to sell my Mac. I did not pay over a grand for a computer that has consistent, unfixable internet problems.