Hello anc.m,
Which version do you use? This bug has been fixed since version 1.2.1.
Do you use any extension which change the functionality of the cart? It is possible that there is collision. You can try to do a little test:
1) Copy the file 'Renderer.php' (extract it from attachments) into 'app/code/local/Artio/MTurbo/Block/Checkout/Cart/Item/Renderer.php' and overwrite it
2) Enable the Magento system log. (System/Configuration/Advanced/Developer/Log settings)
3) Cache some page by MTurbo.
4) Look into the system log file (var/log/system.log)
If there is no record from MTurbo then block isn't rewrited and probably there is collision with other extension. In this case it needs to find a collision extension a fix it.
If you will have any problem, we are ready to help you.
jich