XP will not start after expanding Harddisc on guest system.

[no51]

at first it look like it worked as I could restart without problems. I then let it make updates as windows wanted. after that it's impossible to start the guest system. even VB itself is unreachable. only if I close the session it's possible to edit in VB. the XP is the only guest system and there is no shapshots. How do I get in touch again with the XP guest system?
host is a Mac pro lion 10.7.2 with 2x 2.66 and 7 GB Ram and 1 TB hardddisc space. From the beginning the XP was setup using standard setup.

[Etepetete]

Insert the XP installation disk, boot from it and try to repair the installation. There is no guarantee that it will work, but that is what I'd do if the problem existed on a physical machine.
Just a suggestion, it is always beneficial to have backups of your VMs. Once you get your issue resolved, make a backup and keep it in a safe place. Make new backups after major updates to your VM. It makes life easier in the future.

[mpack]

even VB itself is unreachable. only if I close the session it's possible to edit in VB

It is normal that the VM settings are unavailable while the VM is running.

As to the nature of the problem with the VM, more information on symptoms or error messages would be useful. Are you absolutely sure you made no changes to VM settings prior to the problem?

[no51]

It's up and running again. Yes I made absolutely no change to WM prior to the expansion.
first I have to put the xp cd in the drive (no repair, it just sit there) and after that I have to set the boot order to HD first. after that it works without a hickup. I then try to make the DVD-drive passthrough and again it stop with a black screen not even the boot screen with F12 appear. then I kill it and unchecked the passthrough and again it works fine.
Etepetete: your advice is noted, have cried enough