error at emulating drive (WinPE)

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Hi all,

I am using iPXE for a while now and I am having some problems with a machine.
When I change the IDE controller from IDE to AHCI the WinPE images freeze at:

emulating drive 0x81
entering bootmgr.exe with parameters at 0x02a390

All the other machines boot correctly with no problems at all.
I use a pre-built binary from rom-o-matic.eu with my own script.

I've tried different output files and the .pxe one boots but the hard drive is not recognized when Acronis or Ghost loads up in WinPE.
When i reboot the machine and enter the BIOS the hard drive does not get recognized anymore. To fix it i have to disconnect/connect the drive again.
Also i've tried to use different versions of wimboot and other bootmgr.exe files that sadly dont work either.

I am guessing this is a hardware related problem but maybe you guys got an idea?
The machine is a POS (Senortech) with an Aptio BIOS and a Realtek B01 D00 NIC.
When i set the protocol on IDE everything works flawless.
thanks in advance!