I found a solution for this.
I had an iso-file specified in all of the VMs CD-ROM although it wasn't connected. The iso-file was on a NFS-share that was disconnected.
For some reason I couldn't get it to connect again and I couldn't remove it either as the VMs was using it.
On some VMs I could use the vSphere desktop client to remove it but most VMs showed the CD-ROM as "restricted" and I couldn't change any settings.
I couldn't make any changes in the Web Client as the disks where all messed up with the snapshots so I couldn't save.
Then I figured I could use "Install Vmware Tools" to make it mount that iso-file instead (Interactive Tools Upgrade). When I had done that I could create a snapshot successfully and open the snapshot manager and "Delete All".
I had to end the Vmware Tools installation after the snapshots where deleted for the next VM to be able to make a successful snapshot for some reason.
I have 4 more VMs to go but so far it's working.
Hopefully someone else will find this post helpful.
