This appears to be a problem under OSX. It doesn't happen under Windows and I haven't tried it under Linux.
On a MAC, when you scroll to the end of a page of source code, that page is closed and the IDE automatically switches to the next open tab of source code. If I scroll too quickly towards the bottom of the page of code, the next page of source is not opened, the IDE goes into a loop and eventually crashes with an error report being sent to Apple.