I contacted the hosting company about this and they have corrected the problem for adding entries with urls in.

"This is due to the mod_security rules installed on server for security reasons."

However, I still can't seem to get links to work in comments. They just don't appear as clickable links ...

When I create a new entry with a url in it and hit the save button, instead of saving the entry, it jumps to the home page of my website. The same happens when you try to put a url in a comment. This makes it impossible post any entries or comments with links.

Can anyone help?

You can see the ...