To reboot your mobile device, press and hold the sleep/wake button. After a second or two, the slider will appear. You just need to drag it and reboot your phone. When both, computer and iPhone are on again, try to connect the phone to the computer.
As you know, your Windows OS should be regularly updated. If there are some new updates, download them, and let your computer do its work.
It is important to have the iTunes software which is up to date. Before any restore or update of your iPhone, check if there is a new iTunes software version available. If there is, get it and install it.
On the keyboard of your computer, type Ctrl + Alt + Delete. The task manager will open. Find Apple services such as iTunesHelper.exe, iPodServices.exe, and AppleMobileDeviceService.exe, click on the service, and choose End Process. Reboot your computer.
The reason for why you got the error may be the outdated security software. Check if there is a new version available, and install it.