If I understand this correctly you created a snapshot tree and go back and forth in it!? Please post a screen shot of the Snapshot manager window and explain which snapshot causes the issue. In addition to this, post a list of files in the VM's folder, compress/zip the .vmx, .vmsd and vmware.log files and attach the .zip file to a reply post. If you are using 2GB sparse .vmdk files (with .vmdk header in separate files), please add all the header .vmdk files to the .zip file too.
André