I'd rather check if this has been isolated previously before I go enabling/disabling addons for the next 3hours to check.
I'm currently unable to close frames like raid, guild, spellbook etc when I open them in combat. I have a habit of checking the guild pane while raiding so being unable to close it is quite an annoying issue.
Any ideas which addon is likely causing this? I'll post a list of my addons folder if needed.
Step 1: Get something like ACP or MCP if you don't already (to enable / disable addons in-game)
Step 2: Disable everything (except MCP) and log in, go to some lowbie zone and aggro baby mobs, make sure the problem dosent still persist (it wont)
Step 3: Start re-enabling mods (preferably one at a time) and then checking to see if the bug comes back.
Something is causing your other frames to get tainted, and thats the best way I can think of to track down the problem. There might be an easier way to see what's tainting what but I don't know, sorry.