Whilst it won't solve the cause, have you thought about putting PC in standby overnight? Does mean its not fully shutting down and will start up quicker, unless its going to be several days between use, you don't need to turn it fully off.
Hold the windows key and hit "r".
Type "msconfig.exe" and hit enter.
On the startup tab, go through the programs that are being started, google each one that you do not know about.
Selective removal from boot of some of these applications can speed up your boot process.