Windows 8 fails to boot after installing Ubuntu

I just installed Ubuntu 14.04 (in UEFI mode) on a brand new notebook PC with Windows 8 pre-installed, somehow corrupted Windows boot configuration data on EFI system partition as it seemed and fixed the BCD at Windows command prompt with bcdboot C:\Windows (C: is the drive Windows 8 is installed on). Now I'm presented with a different error message during boot:

The operating system couldn't be loaded because a critical system driver is missing or contains errors.

File: \windows\System32\Drivers\acpiex.sys

Error code: 0xc0000221

But the file mentioned just sits there, and I don't think it can possibly be corrupt, since everything was fine before installing Ubuntu.

I think the Windows loader, winload.efi, fails to locate the partition containing Windows system files. Any ideas?