Edit post to add link to url not saving

Hi I have tried to edit a post to make a pasted url a link to open in a new window and it will not save my changes.
Below is an example of my post where I tried this.
http://cs.finescale.com/fsm/modeling_subjects/f/29/t/162947.aspx?page=23

I have also noticed this too on editing my signature. I tried setting a url and an image with a url and neither would save.
This happens in both Chrome and IE.

Any suggestions and or can anyone else replicate this activity?

Cheers,

-Colin.