So for a while I couldn't access RMON statistics, or VLAN port membership, but if I clicked on other pages, I could access them. The problem seems to degrade... eventually I wasn't able to access anything. A power cycle of the switch cleared it up. I'm using firefox 220.127.116.11 running on a Solaris (Solaris Express b62, in case anyone is counting) system. It appears that if I wait a while, whatever bad data is being cached times out, and I can access things again. I've not timed it precisely yet, but I'd guess its on the order of 10 minutes or thereabouts.
I will say this; this is one of the most annoying bugs I've run into... I write NIC drivers, and I need to change switch the configuration quite frequently. Not being able to do this easily is causing me a lot of grief. I'd gladly trade the "snazzy" features on the web interface for a simpler/uglier interface (web or cli) that worked reliably.