I agree, nothing in WordPress would specifically target and change a value like that. Is it happening as soon as you refresh the page after saving?
So you save your own ID then on refresh again it changes or does it change randomly?
You should troubleshoot and get more information for us.
Please confirm the plugin you are using?
Also, did you update your plugin and could it simply be the plugin resetting the value?
Create a new blog, no plugins etc. Can you confirm it happens when no plugins are active and this would rule out plugins causing it?
Search the value 00000000000 in your code using Windows or Dreamweaver. Anything that will search a files content, this could possibly locate the file with a script that updates the value.