I used to his this problem with my old Laptop. It eventually resolved itself but to my understanding it was a disk error that was keeping it at the screen for such a long time.

There are a few things could try to solve this.

1) Run TFC.exe as administrator (Temporary file cleaner), Just search it on google and you will find a DL to it.

This will clean out any temp files which may be causing an issue with your HDD

2) Run CCleaner, again, download from google

3) Run Malwarebytes, again, download from google

Run a quick Disc Error Checking on the drive your OS is installed on.
To begin the scan, right-click on the Drive which you wish to check and select Properties. Next, click on Tools tab and under Error checking, click on the Check button. This option will check the drive for file system errors.

^ I forgot about that. Nicely put.

Quick way to do this - run CMD Prompt as admin and type in "chkdsk /f C:"

You could also try running a chkdsk on the C:/.

Open CMD as Administrator, type chkdsk c: and see if it brings up any problems.

You could also trying doing a sfc /scannow which will perform a system scan to check for any problems.