Re: filladapt mode stops filling after lengthy amount of emacs uptime

[Richard Stallman]

    Anything I can do to help debugging?

    JDO

    Debugger entered--Lisp error: (invalid-regexp "Regular expression too big")
      looking-at( ... )

The debugging has to start with debugging filladapt, but filladapt is
not part of Emacs.  Debugging this may or may not lead you to an Emacs
bug.

I suggest starting by looking at that regexp.  Is it really too big?
If so, you could try to see why filladapt made it.