I would therefore think your problem is probably something else.

But if you can show that there are cases where "/" won't work on Windows, please try to isolate the problem and post a demonstration here.

And while I am at (this is not addressing your problem but maybe someone else may find it useful):

1) It's probably best to use File::Spec to build path-expressions in a portable way.

2) If you want to build a path-expression for windows using "\" as separator keep in mind that you cannot simply do "$dir\$file" (which is not syntactically wrong but probably won't give you the path you want).