Win7 will not shut down

Hi, I've had this problem for a while, it only happens sometimes. But basically windows does not shut down. I click "shut down" and it goes through logging off and gets to the blue "shut down" screen but doesn't do anything. For example today I clicked shut down at 8:35 and I just got back at 14:40 and its still at the blue "shut down" screen with the circle that spins around.

I don't know what it is and I have no clue how to fix it. Does anyone have any ideas?

Software running at the time of shutdown or old drivers.

Uninstall any lesser-known software and update drivers.

Hi Guys,
in am a new member on this thread.
my situation is that Windows 7 will not shut down from one LAN i connect to in Wireless or Cat5 connection. On all other LAN's it shuts down normally.
If I use my service providers USB air port in the same environment with the wirless switch off and the Cat5 disconnected everything works as expected.
The only way to shut my computer down when connected to either wirless or Cat5 connection in this environment is to hold the start button down. when it boots up again it notifies me it did not shut down correctly.i
ALSO the USB ports are not functional on the same LAN on all other LAN's the USB ports operate normally.
ALSO if I leave my computer for some time I get the DREADED BLUE SCREEN.
Any help would be appreciated this has been annoying me for months.
Tim