Odd. My airport extreme is running just fine with my n800.
Of course it's running in bridge mode, b/g/n mode, and using WPA2 only with MAC filtering.
Using a new macbook pro and n80i with it as well, sometimes all at once. No reboots. N800 has the latest firmware with the SDHC hack and booting off the internal 4 GB SDHC card.
Try setting another router and using the extreme in bridge-only mode.
I do know my n800 won't "see" the extreme if it's in wpa/wpa2 mode, only in wep or wpa2 modes.
Typed this all out on my n800, btw....no airport extreme reboots.