How to Delete Huge Folder Containing Files with Invalid Names

A crash filled my Firefox cache folder with tens of thousands of files
and subfolders with invalid characters in their names. As a result, I
can't delete the folder.

Here's what I tried and has failed so far:

Moving folder to recycle bin
Renaming folder to cache.tmp and using a utility called "Empty Temp
Folders" to delete files
Trying to delete files in the folder from a DOS command line prompt
Trying to clear the cache from Firefox
Making the cache size preference very small, closing and opening Firefox
Using System Suite, a disk management utility
Using DelinvFile, a utility designed to delete invalid files
Using PurgeFox, a utility designed to clear the firefox cache,

Sometimes these methods hung, and sometimes they returned error messages
about invalid file names, locked files and denied access.

I really want to get rid of this junk. Can anyone tell me how to delete
the folder and its contents or recommend a program that will do so?

Thanks.

Ellen