What you need to do is to reset everything to the default values in the .alice file, which should be in a fairly top level directory.
I think Gabe posted a message on how to do this about six months ago but I couldn't find it with a quick search. (Maybe he can find/repeat it.

)
What I usually do is just run "slow and steady" Alice - this usually (not always) resets whatever parameter that is causing the problem back to it's initial value. (Never have figured out exactly what causes the problem.)
If not, all parameters will ususally reset automatically after a day or two (something to be carefull of if you
want to change the parameters - say to enable scripting).