While I can't say if my issue is exactly the same as yours, I did have a similar problem. I ended up having to uninstall both the video drivers and the IRST package before performing the upgrade. With those two variables removed from the equation, it upgraded just fine.
Finally solved it (somewhat). Ran the Upgrade advisor and found that WinPCAP that I used with UV Realtime wasn't compatible. I uninstalled it, cleaned up some old Acronis installs, repaired DRM, and Disabled all startup items except for Microsoft Services. Here's why I say somewhat solved... After the upgrade because all of the startup items were disabled except for Microsoft Services the registry entries and startup menu items did not carry over to Windows 8. I'm having to do a manual rollback and reupgrade again to see if I can recover them. P.S. I hate days when I'm sick!
It's really a PITA that the upgrade advisor is not integrated into the W8 Setup, i actually had to download it as well to see whats compatbile whats not on my netbook as the Setup itself was trial&error, awful decision from Microsoft, first create such a nice tool but then it's something you have to download, it doesnt ship with the dvd or integrated into the Setup
Its truly nothing new. Microsoft did the Same exact thing when they went from XP to Vista (Windows Vista Upgrade Adviser), then XP / Vista to Windows 7 (Windows 7 Upgrade Adviser) and now XP, Vista, and 7 (Windows 8 Upgrade Assistant). Its like an old dog doing the same trick...
Well just a small update. I tried rolling back to Windows 7 using some guides I found and nothing short of crashed my whole system. I'm moving the Windows 8 files back over as I found how to possibly restore my missing startup items using some registry keys now. UPDATE: Windows 8 restored and booting fine. No loss of data!
Well after much time creating a *.REG to import all my startup items back I finally fixed it. By looking at the two locations below in the registry I was able to parse through and use the "item"="", "command"="", "hkey"="", and "key"="" values to make a *.REG that recovered all of my startup items. Startup folder shows where it backed up the *.LNK files and where they belong so I was able to move them over and remove the extra *.CommonStartup or *.Startup extensions and they worked immediately. Now all I have to do is clean up the folders below and I'm good to go! HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Shared Tools\MSConfig\startupfolder HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Shared Tools\MSConfig\startupreg