In big Manual Test Lists with many Manual tests in it, moving to Next Test/Previous test pretty fast heaps the memory ussage and Manual Runner crashes with Out of Memory exception eventually.

Note: if you slow down navigation and save results between navigation steps, memory is released and issue is not observed

Workaround: A temporary workaround is on a 64bit machine to increase the memory for the Manual Runner application as shown here http://docs.telerik.com/teststudio/user-guide/knowledge-base/oom.aspx