Firstly, I confirmed that the OOTB HTML editor does indeed strip any scripting out – you can paste code into the HTML view of the editor but as soon as you save it any code gets stripped out, but basic HTML formatting gets left behind.
I’d forgotten about earlier issues I’d experienced with <form> tags in SharePoint and next tried pasting my code into the Telerik r.a.d. editor for MOSS Web part, only to meet the dreaded ‘error – return to site’ page. My only escape was to kill the Web part by going into the Web part maintenance page and closing it.
Next, I copied my code into the CEWP, source editor (which I’d always used for adding script to individual pages) and BINGO…that’s when I remembered the issue with <form> tags – see below. I also remembered having had this issue in SPS2003.
Once I stripped out my <form> tag, the code was also successfully placed in the Telerik r.a.d. editor.