drupal_urlencode() turning 'http://' to 'http%3A/%252F'

Hi,

I'm in the process of writing a module and I cam across this odd bug, when I pass my a URL as a string through drupal_urlencode() it is converting the 'http://' part into 'http%3A/%252F' instead of 'http%3A%2F%2F'.

When decode, it returns 'http:/%2F' instead of 'http://' which creates a big problem for my module.

Maybe it's something to do with my module/environment as I would have thought that a bug such as this would cause big problems globally.

Any help would be appreciated.