blender crashes

How many crashes tells you something is wrong? 5 in a work day is what I get with 2.5 and 2.6. 2.4 works fine . I upgraded my computer about the same time I started to use 2.5+ more then 2.4 but the new mobo cpu ram runs windows well.

2 Is ubuntu/ linux more stable with blender? Is the render time the same?