The problem I meet is when I try to edit the code in .nb file, the Mathematica often crash and "Not responding" shows after the file name in the top line, especially when I want to copy some code with mouse. Generally, I need to wait for a while then edit the code again. Then the problem still exists. There is no such problem before. My system is Windows 8 (64) and I have tried Mathematica 10.0 and 10.2.
Is there anybody having the same problem and know how to solve it?