It could be some program that’s running in the background which is causing this. Use
Msconfig to remove unused [or partially used] programs from windows start up. Click on the link for
How to use MSCONFIG in Windows 7 guide;
http://netsquirrel.com/msconfig/msconfig_win7.html
(Do not remove your Anti-Virus program from start-up, as well as Java ™ from Sun Micro System, and programs from Microsoft/Intel/AMD Corporations).
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Check your components manufacture website for
latest drivers, especially graphics.
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Also download and run Malwarebytes Anti-Malware, to make sure there’s no malware in your system. http://www.malwarebytes.org/
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Last but not least Run System File Checker, to make sure your system files is not corrupted.
To Run System File Checker, do as follows;
Click on Windows Icon
In the search box type
cmd
Right click on cmd and click
Run as administrator
Type
sfc /scannow
(it would take between 5-10 minutes to do the scan)