2008R2 Host with Win7 Guest shows black screen

[Skymag]

@noteirak:
I try to send F8 but the black screen appears so fast, that the command do not come in.
It is so fast, I think it is before Windows starts - so there must be an error "under / before" Windows, or what you think?

[noteirak]

You need to make sure the F8 gets just after the HDD was booted, and the only way to do so is to spam F8 from the moment the Virtual Machine is started (you'll see the Virtualbox logo) until you see a black & white menu giving you the options of booting. If you only press it once, you'll miss that very precise split second.

Can you confirm you are spamming F8 until it is obvious that the machine is not starting?

From what I can see, there is nothing wrong with the virtualbox itself, your windows boot sector could be corrupted or something like that, which means you would troubleshoot this the same way as for a normal machine : put in the Windows CD/ISO and try to fix the boot sector and bootmgr, partitions tables...

[Skymag]

Yes, I spammed with F8 but still got the black screen.
Now, I think I had to try it on another hardware platform with more GB RAM, with 512MB it will work to slowly.

Thank you for your tips, Skymag