Never had this problem before but today when trying to change tab name Omniscope hangs.
Using version: 2.7 build b333 1 May 2012
May possibly be caused by use of Thai script which has been used to name the tab being duplicated. But problem also occurs with English script tab names.
I am experiencing the same problems since updating to build b333. Adding DataExplorer tab is a bit slow in this file considering the file is not that big and I have 8GB RAM.