If you've updated FFTPatcher versions (or are using an older version), there may be files that you need that aren't present.
It looks like an error relating to XML, did you customize any of the *.xml file hacks or anything else with that file suffix?
If you did, could you open them in Notepad and count the number of open arrows "<" and close arrows ">"? If they aren't the same, you accidentally deleted or added one. The find or find/replace functionality should list the number of occurances of a search string, if not download notepad2 or notepad++.