[plt-scheme] PLaneT question

Hello all,

I showed students something that involved a (planet ...) require
statement. For many of my students (under Windows XP), everything went
fine. For just one of them, the require fails, and the claim is made
that:

open-input-file: cannot open input file: "C:\Documents and
Settings\rnancollas\Application Data\PLT
Scheme\planet\300\371\cache\schematics\schemeunit.plt\2\8\test-ui.ss"
(The system cannot find the file specified.; errno=2)

Oddly, the file exists. The path exists. In truth, I don't know what's going on.

I had the student delete the entire planet subdirectory, re-run the
code including the 'require', and ... the error persists.

What can I recommend to my students so they might be able to
successfully include this code? I spend my time working on the Mac or
under Linux, and am at a touch of a loss for what could be going wrong
where that would cause this require statement to fail in this way.

They're running a Windows DrScheme 371 installation.

Many thanks for any insights,
Matt