performOnServer: fails if TMP not writable
The method System class >> performOnServer: creates a temporary file
in C:/TMP during processing of the command string. If C:/TMP is
not wriable by the user, this method will not return an error, fail
to perform the desired operations, and return an empty string.
Workaround:
Change the environment variables TMP and TEMP to a directory that
the user has full access to.