VM Shows Black Screen After I Changed UUID

[RooF]

Host: Windows 7 Enterprise 64-bit, Vbox 4.0.10 PEUL; Guest WinXP SP3 IE7 No Office;
I manually copied several vhd's to my current host machine. I originally ran into the issue of repeat UUIDs.
After running the command VBoxManage internalcommands sethduuid "filename", I was allowed to load my guest VM WinXP SP3 IE7 No Office;
once loaded I selected that specific guest and pressed the green arrow marked "start";
My XP SP3 IE7 No Office [Running] - Oracle VM VirtualBox screen pops up and goes through the bios load screen that VirtualBox runs;
Then, I get nothing but a black screen, the WindowsXP loading screen does not appear even after several minutes of waiting;
I'm not sure where to go from here and any help would be greatly appreciated!
If you need any further information please don't hesistate to ask.

[mpack]

It sounds like you changed more than the UUID - it sounds like you changed VM platforms too.

Anyway, turn on the IO APIC setting in the guest.

Note that there is no guarantee that VMs copied from Win7 or VPC will work in VirtualBox, even though VirtualBox can read the media.

[RooF]

Thank you for such a speedy reply.
I did not change the VM platform I use.
I also turned on the IO APIC like suggested and I am still loading into a black screen.
I have a guest: WinXP SP3 IE6 No Office that works; it was due to this guest that I had to change the UUID for WinXP SP3 IE7 No Office; The only steps I took for changing the UUID was to run the command "VBoxManage internalcommands sethduuid 'filename' ";
Any other suggestions would be appreciated or if any further information is needed please don't hesitate to ask!

[mpack]

I did not change the VM platform I use.

Then why are you using VHDs? A VM created on VirtualBox will not use the VHD image format by default. Although possible, the procedure by which it could be done would be cumbersome, and would have no benefit that I'm aware of, so I'm not sure what reason you would have had for doing it. You certainly couldn't do it by accident.

[RooF]

My apologies let me clarify, the original vm was created on a different platform but since then I've started using virtualbox and have had no issues until I tried to transfer to a different host.
If the file being a vhd is an issue I have software that will allow me to convert it to a vdi.

[RooF]

Thank you for all your time and consideration, my issue has been fixed!

My original vm's were not run through virtualbox.
I restarted from scratch; once WinXP was installed I used CloneVDI to make several copies so that I could have different versions of software within WinXP (IE6, IE7, IE8 etc)
I then copy and pasted the folder with the "filename".vbox (created by virtualbox) from the old host to the new host machine;
When I ran the .vbox for the first time I ran into this error:
Failed to start the virtual machine "filename".
VT-x is not available. (VERR_VMX_NO_VMX).
Unknown error creating VM (VERR_VMX_NO_VMX).
I went into the settings under system and unchecked "enable IO APIC"
When I started my vm it went in to the black screen issue I was having before
I went back into settings under system and checked "enable IO APIC"
The WinXP VM now runs fine with no more issues!

Thank you for all your time and consideration, my issue has been fixed!