After editing a line of single line text and hitting the return or enter keys the graphics area of the screen appears to stop responding (i.e. the screen is not repainted/regenerated).

Toolbar buttons etc, are still working - the program has not locked, for example if you attempt to draw a line on the screen it is being created - but you can’t see it.

System Specification:

Dell Precision T3600, Intel Xeon CPU, 16GB Ram, Windows 7 PRO (64 bit), AMD FirePro W5000 graphics card.

UPDATE 19th November 2014

This only happens when you use the WYSIWYG editing of single line text, if you edit the same text using a dialogue box the problem does not occur (NoteOptions command can be used to switch between WYSIWYG and dialogue editing of single line text).