Arduino 1.6.8 always reset boards

[wwwusr]

Hello guys,
Use Arduino1.6.8 in Win7 64,I plug 4 Arduino boards:2 Pro mini(through PL2303),1 Nano,1 Uno(all uses CH340G),when I open the 1.6.8 IDE,all board's 13 LED will flash,means that the boards are all reset time an time again,and sometimes can upload codes,but sometimes can't do that.
And,1.0.5 IDE version is OK, after run 1.0.5,all boards run stable,even run some codes throuth serial port.

[wwwusr]

Version 1.5.8 is OK,tested

[PaulStoffregen]

Any chance you could test with a genuine Arduino Uno? It uses the 16u2 chip, not ch340.

[facchinm]

Closed by merging #4792, try the latest nightly build and the problem should disappear

[wwwusr]

Thanks!I'll try like that