[plt-scheme] Strange problems with compilation

I'm having the following bizarre problem with the compilation of Typed
Scheme.  When, in DrScheme, I try to run a module that uses Typed
Scheme like so:

(module foo "typed-scheme.ss")

 I get the following error:

compile: variable not provided (directly or indirectly and at the
expected position) from module:
|,/home/samth/work/typed-scheme/private/typechecker-unit| in: u.1

This usually means that the zo file for typechecker-unit.ss is out of
date.  But when I rebuild the zo files for that file, it never gets up
to date.  I can rerun mzc -k on the file as many times as I want, and
it always recompiles it, and the error never goes away.

If I remove all the compiled code, I get this error instead:

private/typechecker-unit.ss::15201: map: expects type <procedure> as
1st argument, given: #<struct-type:def-stx-binding>; other arguments
were: ()

The error points to a place in the source where map is applied to
something that's definitely a procedure.

If I require the file from the MzScheme repl, it works, regardless of
the state of the zos.

I'm very puzzled.  Does anyone have any ideas?

-- 
sam th
samth at ccs.neu.edu