I had an issue where pc starts to boot than pauses for 40 seconds while Windows logo and dots are spinning, no harddrive activity and keyboard and mouse are powered off, after 41 seconds boot proceeds as normal. I used Windows Performance Analyser as per this post.
Investigation in Windows Performance Analyser shows Pre Session Init taking 41 seconds mostly doing idling.
Some process activity was detected at ntoskrnl.exe and ACPI.sys which led me to believe driver initialisation issues.
