I ran into this on some routers. The poor owner was insisting it was not the router so we left them to stew (get more tender and open to suggestions.)
The fact it worked fine at other locations didn't dissuade them it was not their laptop.
I read your post TWICE and can't find the details about the router, settings to offer anything more.
I have an Acer "netbook" (Aspire One D260), and I connect to the Internet via wireless router and cable ISP. The longer I'm online, the more likely I am to have my connection dropped (like almost every day). I have tried repeatedly every solution I could think of including rebooting the router, calling the cable company, Windows 7 troubleshooting process, clicking "disconnect" then "connect" multiple times -- nothing works. Rebooting the machine works EVERY TIME. Where does this indicate the problem lies? Is this typical? It's the first computer I've ever had this problem with. I don't know if it's significant, but I've had a computer technician point out to me that this machine runs with much lower than usually available physical memory.