If you are on Sitecore 7.2 (i tested that with Sitecore 7.2 Update-2 and Sitecore 7.2 Update Initial Release) and tried to use the Insert Link function in the Rich Text Editor using the Search Tab, you maybe discover that bug too.
The link generated from the result of that search is not the selected item, but the item selected in the Internal Link Tab.
This is a bug and confirmed by the support.
If you need more information on how to solve that, support has made a package which you can ask with the Ticket number : 418048.
Thanks to Ivan Sheyenko & Sergey Plashenko which work on that issue