Right with you but I think what essexboy means about this tool is not only about malware issue but log may help to understand where the issue came from , maybe (I don't know) recovers an aviable registry to boot again normaly
Like you said before , when your boot is near dead (even with safe mode) you have no many possibility , so there are only few tools to access HDD (UBCD?),and thanks essexboy to purpose one I never seen before (just avast say OLT.exe is not very sure
)
Nb:I tried this morning FRST on my pc (OS mounted) and ".txt" let me see a lot of my last month history like registries error , files deleted / modified when pb occurs .....
All analysts below are volunteers and are not associated with Avast
thanks
maybe less hotline than avast but sure more effective