My computer started lagging last Sunday. I tried to reboot it and it failed.
Trying to boot into failsafe mode takes around two hours. It mainly freezes on two files: scsiport.sys and classpnp.sys
When it finally has started all disc operations are really slow. When it has run for a while it goes faster, probably due to data moved into RAM instead.
It froze on an other file before that was associated with Avast but uninstalling it didn't really help.
A critical windows update was installed on Sunday but rolling back the update didn't help. I had a guess about the sound card but disabling the sound card drivers also didn’t help.

I have an inkling of an idea that it might be Intel rapid storage technology that might be acting up but it doesn't allow me to reinstall it from failsafe mode and I haven't been able to log into normal mode for a while.
I would appreciate suggestions regarding how to get into normal mode again and/or what can be the root cause.