First we need to determine where the fault lies - in hardware or software of the computer. In the first case, to detect faulty components in the computer you must boot under another OS. It is quite suitable for a LiveCD or installed to a different partition of the disk operating system. If the problem persists, the problem lies in the hardware of the computer. Testing of component parts is possible only by replacement on obviously serviceable.

If the fault in the hardware of the computer is not detected, you can proceed to verify, although in most cases the test should start with her. Delaying the turn-off process can occur with faulty drivers. In this case, can help them reinstall.
USB hub

Often hangs when shutdown occurs due to improper installation of Windows. Especially often this fault is found in laptops caused by the controller of the IEEE 1394 bus. To eliminate it simply put a tick in the settings hub.
Also freezes when disconnection may occur when a computer is infected with malware. To check you need to download a fresh antivirus database and scan your computer. The test it is desirable to produce at least two anti-virus utilities. Perfectly cope with this task Dr. WebCureIt or AVZ 4.
If after all the above steps, the shutdown process is always long, the problem we need to look at recently installed applications or system services. It's likely that one of them causes a conflict in the system. Viewing the conflicting application or service possible in the event log. Generally disabling the service or uninstalling the application (if there is a particular need for them) resolves the issue. Also at the time of shutdown of Windows is affected by a number of programs at startup.
Hang at shutdown can also occur when a failure of the BIOS settings. In case you see the text "Now the power of the computer, you can disable" in the BIOS, under power management, you must enable ACPI. Also, in some cases, may help reset to factory settings.