Error loading stringproc



Trying to do some work with strings, in Maxima 5.15.0 (clisp), I got:

Load failed for
/usr/share/maxima/5.15.0/share/contrib/stringproc/stringproc.lisp

When I set debugmode(true) and tried to load stringproc again:

Load failed for
/usr/share/maxima/5.15.0/share/contrib/stringproc/stringproc.lisp
 -- an error.  Entering the Maxima Debugger dbm
Enter `:h' for help
(dbm:1) :step
Load failed for
/usr/share/maxima/5.15.0/share/contrib/stringproc/printf.lisp
 -- an error.  Entering the Maxima Debugger dbm
Enter `:h' for help
(dbm:1) :step
Load failed for
/usr/share/maxima/5.15.0/share/contrib/stringproc/pregexp.lisp
 -- an error.  Entering the Maxima Debugger dbm
Enter `:h' for help
(dbm:1) :step
Load failed for
/usr/share/maxima/5.15.0/share/contrib/stringproc/pregexp.lisp
 -- an error.  Entering the Maxima Debugger dbm

What's going on - is this a lisp problem, or a Maxima problem?  Actually,
all I want to do is to read a string and obtain the characters one by one
from it - maybe I could do this directly in lisp without loading stringproc?

Any advice would be most welcome!

Thanks,
Alasdair