file uploading class problems

[eluser]ferno[/eluser]
hi, i just tried out the file uploading class 'tutorial' in the user guide, and it almost works.. lol

when i hit upload with no input (empty text box) i get the correct error: 'You did not select a file to upload'

but if i keep hitting upload the error does not show up anymore and my url goes crazy!

after hitting upload 5 times my URL looks like this: http://localhost/index.php/upload/upload.../do_upload

the same thing happens if i try to upload a file that is not of the right type...

btw i copied the source code from the user guide EXACTLY into my fresh install of CI

any tips?