Power switching problems

I know a guy posted this problem before but he didn't say how he fixed it so I am asking again. When I plug my computer in when windows is on it locks up and freezes. It doesn't do this when I unplug very often but every time when I plug it in. Also the screen on/off function button doesn't work.

 

I had this same problem and from what I figured out it is the video card "underclocking" itself when you take it off of AC Power, and the "Overclocking" it self back to the default.. I think it's just too big of a leap for it to handle.. The defaults for the video card is 300/200 when you unplug it ATI Powerplay kicks it down to 100/100 and then when you plug it back in Powerplay kicks it back up to 300/200 or whatever if you have it overclocked. So all you have to do is turn Powerplay off.

Right click on desktop go to properties / settings / advanced / Powerplay(tm) / uncheck Enable Powerplay(tm) and you should be good to go. No more locking up.

 

Thanks a bunch