Since I bought my WZR-HP-G300NH, I've constantly had to reboot it every few days. Some of the issues I encountered were: compatibility with certain network cards, dhcp server freezing, dropping wireless clients, etc... I installed the supposed firmware 1.71 uploaded by the previous poster and everything seems to be going ok so far. My router now reports as WZR-HP-G300NH Ver.1.71 (R1.15/B1.03). I haven't noticed anything too different in the GUI so far. I'll post back on Sunday evening to let you guys know how it's holding up.
Edit (10 days later): The router is 95% stable now, I've only had to reboot it once since I updated it and no clients have lost connection yet. It's a big step in the right direction, just enough to make the router useable on a day-to-day basis.