Okay a few things, one you have a ATI video card for when you do 'graphic' things, like look at a webpage, run a movie, play a game, etc. For typing 'letters' or such 2D stuff the Intel IGP will kick in to reduce the power consumption and heat created (laptop need to last longer then 30 min and not burn your legs).
I would remove the AMD drivers through Control Panel. Then download Driver Fusion (or the older Driver Sweeper) and really remove all the ATI components. Reboot, then download and reinstall the latest (I believe Beta) Catalyst (have to scroll down) from AMD.
Download and run Slim Drivers, install all the latest updates for all the other parts you may not realize need updating (it is surprising). but you don't need to reboot until you do the last update
Did you install all Windows Updates? Including options except BING? Check them and repeat till ALL are installed.
Remove whatever AV your using and go to www.filehippo.com and download AVAST! or AVG and do a full system scan - this repeatedly has resolved alot of people issue relying on MS Essentials.
Download Malwarebytes do a full system scan (AV doesn't pick up alot of malware) - this resolved almost ALL other similiar posts to date as most had Malware the AV didn't pick up.
Repeat the AV/Malware scans till the system comes up clean.
Finally a review here
http://www.sharpusa.com/CustomerSupport/SharpCareCenter/DownloadFiles.aspx?modelnum=LC-60LE640U shows there is a Firmware update that needs to be applied. I would download to the firmware to a thumb drive then the manual as well to understand how to update the screen.
Fyi the screen is 120Hz, but the laptop over HDMI can only pump out 60Hz displays. If your using HDMI make sure your set to using 60Hz through the AMD Catalyst Panel (Right click desktop and there is the control panel option). If you wish to do 120Hz (like I do) you can NOT do that with AMD, AMD does not support it, only NVIDIA does, and that also requires using the DVI-D connector not HDMI.
Let me know how things turn out after doing all these steps.