It happens when windows installs updates

How to stop it.

1. Click Start, click Run, type sysdm.cpl, and then press ENTER.
2. Click the Automatic Updates tab, and then click to select one of the following option.

# Download updates for me, but let me choose when to install them

If you select this option, Windows recognizes when you are online and uses your Internet connection to automatically download updates from the Windows Update Web site or from the Microsoft Update Web site. An icon appears in the notification area of your taskbar when the updates are being downloaded. You can point to the icon to view the download status. When the download is complete, you receive another message in the notification area so that you can review the updates that are scheduled for installation.

* When you want to install the downloaded update, click the message (or update icon), and then click Install to install the update.
* If you do not want to install a downloaded update, click Details, and then click to clear the check box next to that update to decline it.

Cheers

David VK4MDX