The main issue seems to be that Windows has left CLisp behind.
CLisp is not active in the way that SBCL is and consequently the
CLisp version I am using (2010) does not interact well with Windows
11.
ChatGPT has this to say
On Windows, the official CLISP 2.49 (2010) binary has a long-standing bug in its file-loading system. When you use (load "file.lsp"), CLISP sometimes passes an invalid directory handle to Windows, producing the error “Win32 error 267 (ERROR_DIRECTORY): The directory name is invalid.” This happens even though the file exists, especially when CLISP starts in a drive-relative path (like C:) or when files are stored in protected or virtual folders such as Program Files or OneDrive. The issue is caused by CLISP’s outdated Windows pathname handling, not by your code or filesystem.
I'll put this request on ice since I have no access to any binary later than 2010. This is apparently when the CLisp site ceased to be actively developed. It may be possible to rebuild from sources a modern version, and I'll accept any pointer to a modern binary. But it is a lot of work for a Lisp not so actively used.
Mark