I'm Using J 1.5.26, PHP 5.3.8, K2.5.5

I recently upgraded from K2.4.1 to K2.5.5

When a user is logged in the front end and tries to add a new article, the can do just about everything except save the article or close the pop up screen down.

I have tried this with different demo user, with different K2 User Group permissions (With edit items, add items, etc all set to yes)
Also tried with different browser and with Mac/Pc, but just doesn't work.

Adding articles in back end works fine.

Any ideas suggestions for me ?

Link to Site Here

Andy