Try following steps, if following does not works you can format your pc/laptop:
1. Disk CleanUp(to remove temporary files)
2. Disk Defragmentation(anlalyze first if it shows at least 8% or more then defragment it).
3. Run CCleaner(download, install and then run)
4. type "msconfig" in run command without quotes
click on "STARTUP" and then "UNCHECK" not required "startup item" and then click apply and then ok after that you will see a dialog box asking you to "exit without restart" and "restart".Choose restart to apply changes.