Need Wi-Fi Help Please

My computer just started doing this and I have no idea why, Where I live my roommates and I have a Netgear Dualband Wireless router.. its a 2.4Ghz G and a 5Ghz N. Well it was working perfectly till yesterday.. I'm the only other person in the house that has a dualband wi-fi adapter so I connect to the 5Ghz N band while my 3 other roommates connect to the 2.4Ghz G band. Well yesterday it started jumping back and forth between connections it will stay connected to the N band for about 5 to 10 minutes then disconnects for no reason the connects to the G band.. then repeats the process over and over.. Well the network was unsecured till I added a password and configured the firewall in the router but these problems started before I did that.. I just did that today thinking it would fix the problem. I thought other people might of been highjacking our wi-fi and kicking us off or something.. I hope this makes sense to yall.. Please help me figure this out.. I've only lived here a month and when I moved in they had all there computers and router and modem set-up where it had the worst reception.. when its supposed to have a 300 ft range thru walls.. my roommate beside me and I were not able to connect at all untill I moved it around and now we all get excellent reception.. Well please help me figure this out.. I'm sorry i was rambling.. well thanks in advance..

Oh Yeah I forgot.. Even though my roommates don't have dualband adapters they are still getting kicked off the 2.4Ghz G band and it will reconnect every few minutes just like me and repeat the process like mine...

Quick question...do you know if you are getting kicked off or is your ISP flaking. I would suggest running a ping to your DW and see if that helps....if you can run this from a direct connected box that would be better. If your ISP is fine then I would suggest changing channels on your 2.4G...you may have some cross wifi.

Have you changed the default user name and password on the router? If not, do it now. It is possible they lowered the power output (some have this feature) on one band, and the dual adapter is going back and worth between the two. Or its just giving a warning that's it about to die...

make sure the nband is set to just broadcast n and not both because if someone connects to the n and only has g it will drop it down to g and make u disconnect....