Steps to replicate in IE (6,7,8):

1. Create a page with only the text:

   {color:red}red{color} Ma
   {cheese} smelly
   {nl:CamelCaseWord} following text
   {nl:http://www.google.com} following text
   

2. Click "Save"
3. Re-edit and click the "Wiki Markup" tab, which shows:

   {color:red}red{color}Ma
   {cheese}smelly
   {nl:CamelCaseWord}following text
   {nl:http://www.google.com}following text.
   

Happens on any macro.

The editor works well in Firefox.