Hi There
I have searched but was unable to find any help. I have built my file over many months and now it will not open (neither the main file or backup). I get an Invalid XML File error.
I hope someone can help me as it will be months of changes lost 
The file may be damaged. Did you try the .backup-after-open.xml version, which should only be written after a successful open?
If all files are damaged, your only hope is a separate backup that you may have.
Hi Chirlu, thanks for your help with this. Your solution worked just fine and I have now seen the separate backup file.
Mods - please feel free to close this thread now.