Question : Hyper-V vhd merge problem.

I had 5 snapshots on one VM in HyperV ( 150GB ), then because of lack of HDD space, I had to delete them with HV Manager, and merge process started... In 4 hours only 2% was complete and I needed this VM to be up, ... so I rebooted the server ( I couldn't stop merging process any other way ). After reboot I can start this VM and it works just fine, but now I can't delete snapshot avhd files and I'm out of space on this HDD. In HV Manager I can't see any snapshots. I cannot delete the files manually because they are locked by System process. I run HyperV on W2K8 Standard.
How can I delete those snapshot files?

Answer : Hyper-V vhd merge problem.

1 & 2) You will adequate free space to get the merge process going. The following post answers part of your question.
What happens when I delete a snapshot? [Hyper-V]
If you can figure out the sequence of VHD and AVHDs, the you can copy them on a separate disk and merge them using the process indicated in the post I provided earlier. The you can replace the vhds and avhds in your VMs with the merged VHD. Backup is strongly advised before doing this. Infact do an export of VM before doing this.

Following are few post that might give insight on what you need to do.
Removing Old Snapshots from Hyper-V
Query; Unfiinished Snapshot Merge Process!
Proper way to delete 2008 Hyper V Snapshots
Hyper-V Starting Server Mid Merge

Hope that was helpful to you.
Regards,
Shahid