Tried to reboot my laptop this morning and it went into startup repair. The diagnostic messages in the log said that both the acpi.sys and volsnap.sys system drivers were corrupted.
I brought up a command window under Recovery options and it placed me in the x:\windows\system32 folder. I wasn't sure why the drive was x: and when I tried changing it to c: it let me do it but when I tried dir to list its contents it said it was System Reserved and it looked empty. I figured that x: was actually the os drive and for some reason had been mapped to x: within the recovery tools.
Anyway, cd'ed into the x:\windows\system32\drivers directory and replaced the acpi.sys and volsnap.sys files with good one's from a USB memory stick (gotten from my desktop PC) , but upon another attempt at rebooting the laptop it failed for the same reason and after inspecting the dates on the acpi.sys and volspan.sys files I could see they had been replaced with the older currupted versions again.
How can I replace these files so they are accepted by the system and not replaced with the corrupted ones?