W7 Zombified and sfc /scannow stalling questions

I just tried to do a System File Check so raised an elevated cmd and entered sfc /scannow and clicked Enter as I usually do. It stalled at verification 74%. Tried again and the same thing. Now I have modified quite a bit of the registry tweaking various things. Do you think that is the reason?

Other issue, every now and again W7 boots up and to all appearances looks normal - desktop, taskbar, icons etc. But it's in a zombie-like trance. If I right-click anything I get a very faint transparent balloon which eventually will fill out and I can then do whatever it is I was about to ask for. Yet things aren't normal My Avast orb isn't rotating, meaning it isn't working. Task Manager is totally empty - no processes and the graphs are flatlined.
I can't find a clue in Event Viewer.
I tried fiddling with MSCONFIG Boot/Advanced Options as in attached pic, as I'm in a multi-boot situation, thinking that perhaps that has something to do with it. Perhaps I should check Detect HAL, as I read somewhere it helps, but haven't the faintest idea what it means, sorry.
But second thoughts are telling me that some software somewhere isn't working right.
Any thoughts anyone? I'm in W7 now because after a few reboots it starts to behave normally.

When there are multiple operating systems installed on the same hard drive partition, Detect HAL searches for the different versions of the HAL that are installed on the computer and adds a prompt that allows you to select which operating system to boot to. About the zombie like thing you're experiencing, I've encountered it myself, I just remind myself that we're still using beta then reboot and sure enough, system goes back to normal. It could be anything that's causing the freeze up, so in these cases, I'd check the Event Logs for clues

Thanks. I thought so. I have EasyBCD setup on the first HDD's C partition which gives me the OS choices and I use iReboot to easily pick which one to boot to next. So I should still have "Enable HAL" checked in both Vista and W7?

Nothing in the Event Viewer regarding the freeze-ups, so I guess it will remain a mystery.

Thanks.

Since you really don't have problems switching between OSes, leaving it unchecked is no biggie. Although Detect HAL's description is for detecting multiple operating system's HAL, it is also used when you've made major modifications to your hardware (i.e. Processor upgrades (single core/dual core), new hard drives, BIOS upgrades, etc.) to tell your OS of the new hardware which normally would require a reinstall of the OS. HALs are like motherboard drivers for your OS It reverts to unchecked after every restart.

Note: Detect HAL can be used to correct systems that are not seeing multiple CPU cores. Newly installed hardwares causing BSODs might be corrected by enabling this feature.

Since there's no indication in Event log, it's just one of those ghostly things that windows gives us from time to time

Very helpful, thanks very much.

You're most welcome