Hi All- just Googled and got this thread.
I'm having similar issues with an old Netgear router and a Senao AP, and to me the prob seems to be linked to the OS, not the browser or router. And the problem seems to "update" itsself into older OS's as it goes. Same symptoms- missing buttons, etc, or I get the complete page but when I enter changes (like login details from another ISP) then the router just crashes.
Problem first noted on my desktop under Windows 7 (build 7000) and FF, confirmed with IE and Chrome. Windows firewall and AVG AV
Then tested on Laptop with same OS, security and browsers, same result.
Tested on both machines and all 3 browsers with firewall and AV disabled, same result
Booted Desktop to XP SP3 with ZoneAlarm and AVG and tested fine under all 3 browsers
Booted Laptop to Vista Home Premium with ZA and AVG, tested fine in all browsers
Since then I have gone to Windows 7 build 7100 and dropped the AVG in favour of Avast. No change.
My Laptop under Vista can now no longer access the devices correctly. I have changed nothing but auto updates are activated.
I accidentally broke the XP install on my desktop so reinstalled it- not as dual-boot but as a Virtual Machine under Win 7 (7100) As a clean install of XP SP3 it worked fine, but auto-updates has now made it not access the devices correctly.
I have also tried an old version of FF (2.0) with updates disabled in these 4 environments without success.
My daughter's machine (XP SP3, FF, AVG, ZA) still works fine