i had the same problem on my machine.
it seems to be a problem with the internal handling of the path in my.cnf (can be found under [XAMPP_HOME_DIR]\mysql\bin) or similar when using another mysql-configurationfile. the interpreter of the path seems to interprete the \t from \tmp as an tabulator-escapecharacter.
1. open the file my.cnf using any text-editor (open it from inside the editor because for example under XP the *.cnf-files are associated with some messenger-things.
2. go to the [mysqld]-section and edit the line:
tmpdir="C:\Programme\xampp\tmp" (or similar)
3. insert an \ before the \tmp so you will get the result:
as an alternative you can create a new directory under your xampp-home like _tmp or so. then you have to change the tempdir-path to the related new directory. but the best way is the first one.
oh, and don't forget to restart your mysql after done this ...
greetings from neu-ulm
p.s: i just saw your installation-path in the title of the thread,
the file my.cnf must be found in
the tmp-directory is under