Hello,

>   Thanks for the response. This is a Squeak2.7 image. I don't have a
> CommandHistory class and I can't find the resetAllHistory method....

  It is likely that there are many things in the trash can.
Try to "empty" it.

  If it doesn't change the situation, try

   Smalltalk printSpaceAnalysis

and view the resulting "STspace.text" file.  If gives, well,
the space analysis and sometimes helpful to figure out what
is wrong.

  -- Yoshiki