Can't open bluray on laptop...

[IronMan]

Hello everyone, and thanks for reading my post here!

My problem:
I can't rip any bluray disc on my Asus RoG laptop, though it works perfectly on my desktop pc with the same external reader.
Asus Laptop:
G551JM-CN105H
Windows 8.1 x64
Geforce GTX860
16 GB Ram
1TB + 24GB SSD

Desktop
i73770K
16GB RAM
256GB SSD + several HDDs
Pioneer bluray burner
Windows 7 x64

Now the external reader:
I had a Plextor PX LB950UE, which stopped reading blurays all of a sudden though I barely used it (burned 20 discs with it - and BTW, this burner CAN'T burn LTH media properly, overrated piece of crap...), so I disassembled it, kept the SATA to USB adapter and fitted it to an internal Liteon bluray reader. That works perfectly on my windows 7 x64 desktop, but not on the Asus laptop...

If anyone has an idea... I'm at a loss here. My best guess is that windows 8.1/Makemkv do not mingle well, or, more likely windows 8.1 does not like my reader, BUT, I CAN read blurays with media player software without problems... Oh, and Makemkv works with the internal bluray reader of the laptop...

[Woodstock]

What does the debug log (see FAQ in my signature) say about it? Without that information, all we can do is guess.

[IronMan]

I have the log here, problem is Operating system blocked access to drive... Needs to be run as admin to access drive. Problem is: I run it as admin already.
Is mkvconv.exe (or something like that...) a "sub-process" of the main exe, and does not inherit it's privileges?...

Debug log started at Sun May 17 11:45:16 2015 , written by MakeMKV v1.9.2 win(x64-release)
Using 524544KB for read cache.
001005:0000 MakeMKV v1.9.2 win(x64-release) started
001004:0000 Debug logging enabled, log will be saved as C:\Users\Alain/MakeMKV_log.txt
001003:0020 DEBUG: Code 100864261 at ebXfwCD+sk_\w)xd:29401451
005010:0000 Failed to open disc
001003:0020 DEBUG: Code 3221225653 at /e?[41&sF8Y9Kx8m]Tf@:213130904
002006:0000 Operating system blocked access to optical drive "\Device\CdRom1". Program needs to be run as administrator to access the drive.
001003:0020 DEBUG: Code 3221225653 at ebXfwCD+sk_\w)xd:213134699

I'm going to try to specify "run as admin" in compatibility properties for makemkvcon.exe and makemkvcon64.exe...

I'll post the results...

[IronMan]

When I try to open a bluray disc, makemkv crashes saying "Failed to open disc"... Then, I cannot access my bluray drive, I have to reboot the computer, and windows 8.1 x64 TAKES AGES to reboot.
Process "makemkvcon64.exe" is stuck, and impossible to kill using the task manager or even Process explorer from sysinternals...

What's wrong with windows 8.1???