While creating new page using MarkItUp text editor to add link we need to write (i don't know is this problem present while using CKEditor, but propably yes, couse i think it's bbcode's fault, not just a text editor):

[url=http://somesite.com]SomeSite's name[/url]

Instead of adding a link, it generates:

[url=<a href="">http://somesite.com]SomeSite</a>'s name[/url]

which is not a working link.

UPDATE:

Ahh sorry, i see that, it's known issue and problem occurs because of HTML Purifier