Don, I think you must be talking about the
Tcl CWD thread-safety bug 710642
My understanding is that it does not
have anything directly
to do with using the Tcl "file" command, and you are not safe from the
bug even if you never use any file commands at all. Zoran does have a
patch for it up on SourceForge, so I guess you could patch Tcl
yourself, but no further comment on the bug there since 2003-04-11.