Render Window Freezes

My 3D Spin

Lately i have experinced that when i move the Render window it freezes and cant be moved, saved or anything.
Although the rest of the program works. So i have to cancel the Render and then delete the Render window from
the small icon on the bottom of my screen and then start again! What could cause this problem? It usually happens
right at the beginning of the Render sequenze like in the first minutes..

 

AJ2112

When this is happening, is image appearing in render window ? 

My 3D Spin

AJ2112 said:

When this is happening, is image appearing in render window ?

Yes. The image has started rendering!

Edited to fix quote

AJ2112

If your not able to move render window, once render image begins, then I have no clue, sorry.  I am unable to move render window, till render image displays, then I can move window around anywhere.