Windows 7 Takes Several Minutes To Boot?

My computer does not run smoothly, and I cannot figure out why. My computer takes upwards of five minutes to reboot, with several minutes on the "Windows is Shutting Down" screen and several minutes on the initial boot. The delay even includes starting the computer in Safe Mode.Additionally, I am having tremendous amounts of graphical problems while running any game I have on my machine, including Rig N' Roll, Nascar 2003, Max Payne, and Skyrim (even on the lowest settings). Random discolored shapes will appear and stretch throughout the screen. Black lines show up and the graphics are so unbearable that I cannot play any games functionally. For example, when going through the very beginning of Skyrim, the screen would turn almost completely white and stayed that way until I exited to desktop.

The graphical problems are not only in games, as even browsing on the internet can cause random thin horizontal black lines to appear across the screen. The lines remain even if I shut off my monitor and turn it on again, so the monitor does not appear to be the problem.I have run full scans in safe mode of Malwarebytes and Symantec Endpoint Protection Antivirus, with no detections of virus, spyware or malware. I don't know what else to do.I have the most recent (as of today) Windows updates with the exception of one. The update of KB 911895: Other Hardware - HID Non-User Input Data Filter, refuses to update.

OS: Windows 7 Enterprise 64-bit.Motherboard: XFX Nforce 680i SliProcessor: Intel Core 2 Quad CPU Q6600 @ 2.40ghzRam: 4 gbGraphics: NVIDIA GeForce 7900 GS 2gb card, with driver urrently updated after running drive sweeper and installing the latest driverAudio: