Easiest way to solve the problem?
/export the config. /system reset. Log in while the configuration is still in a "virgin" state and see if the terminal works now. If so, restore your configuration. If it stops working after that, then /system reset the router yet again, and then run small sections of the script generated by export, each time trying the terminal again before the next section of the script to see if it stops working.
When the terminal fails to come up, examine that portion of the script/config to figure out what option you are setting to cause this behavior.
I would advise you to read up on these commands before trying this. Doing an export from the root location (/) does not necessarily give you a script that will restore your config to the exact same state as before. You may need to rearrange some parts as some parts are dependent on other parts that have been put later in the script. There may also be sections marked FIXME that you should definitely pay attention to.
My advice is, if this is a critical router on your network, /system backup your config first so that if you mess up/get stuck, you can always restore it back to the way it was before. You might find it easier to take the file generated by /system backup and copy it to a different (test-bench) router, and then restore the configuration on there and THEN try out my suggestions (do all your testing on a different, non-production box).
-- Nathan
OK, I was thinking in the same direction as your last suggestion. I was actually planning to make a backup router on a dedicated unit (with rb532c board) anyway and this only brings that forward on my action list. I do need to read in a bit on config backups and so on and probably set up the new unit straight away since most of the config´s I know out or my head by now.
but due other priorities it might take a while before you´ll see the outcome of the ´back to virgin´ procedure on the failing unit.
But thanks anyway for the given suggestions so far....