Just happened again. I tried to return to the Glow Engines Forum after viewing a post there. A little IE window pops up with this:

Java Script Error
Description: 'options' is null or not an object
Source: http://rcuniverse.com/forum/forumid_84/tt.htm
Line: 4

I use the "Jump to:" feature to navigate through the Forums, and I get this once or twice each session. Almost always occurs when I try to return to a forum I've been in, after viewing a thread, but sometimes when I try to "jump" to another forum. So I choose another forum, and try to go back to one I couldn't get into later.

Its not a deal-breaker; just annoying.