c:/hello.txt works in cmd.exe but not tcc.exe

Ran across this while using Ruby, it's trying to execute commands with forward slashes in the path to a file, like c:/temp/ruby.exe which cmd.exe will run but tcc.exe says "TCC: Unknown command c:". Looks like I've got to put my comspec back to cmd.exe <sad panda> Is this something that can be fixed in a future build of tcc?
See if checking:

Option > Startup (tab) > UNIX/Linux-style Paths (checkbox)

solves your problem. Alternately, you could set the value of UnixPaths to Yes in the .ini file, which is all that Option does to that directive when that checkbox is checked (although Rex now discourages the direct editing of that file).