Yesterday I downloaded and installed Processing. I then started going through the "Getting Started" page of the processing.org web site and everything seemed to be going ok. That is until I went to save same code. It just would not save. Every time I tried, the IDE kept responding with the message "Save Canceled".
I had a look around the web site and found that this is a known bug and was reported on the 27.Oct.08.
This morning I discovered the exact nature of the bug. If when saving a new sketch you accept the default supplied filename (i.e. sketch_081029a) the save will be cancelled. The work around is to overwrite the filename given in the "File name:" field, of the "Save sketch folder as..." dialogue box, with a filename of your choice.