Router Replacement with old defective router?

DEFECTIVE ROUTERS? ... brought back to life?

I think I have possibly blogged about this before, or twittered it or something, but it has happened again, and I'm confused!

About every month or so I have to replace my router. It just all of a sudden quits allowing a wireless connection but still allows a hard wired connection, or it will just start locking up every few minutes and I will have to power cycle the router to get internet access again. What I don't understand is that it does this quite often, and nothing I do seems to fix it. I have upgraded the firmware, positioned the equipment away from any EMI waves. I can go in and reset to default, reconfigure it with static ips or with dhcp either one, and it will still give me problems. I have tried to use the routers plugged in to a UPS and without the UPS..... this has been going on with different routers for about a year (if not more!). I have a crate of the old routers in the shed, and what is weird is when the router dies... I can go get another router (that was once dead) and plug it back up ... reconfigure it.. and it will work fine for a month or so until it does the same thing! Is it a conspiracy against me? Is it my ISP doing it because I have too many connections on my dsl line? Am I overloading my routers?.. different routers? Any suggestions?