The permissions for the existing bookmark.xml file is as follows:
/share/apps/d3lphin$ ls -l
-rw-r--r-- 1 root root 1126 2007-10-16 18:04 bookmarks.xml
-rw-r--r-- 1 root root 1126 2007-10-16 18:04 bookmarks.xml.bak
If I understand this correctly the user doesn't have the right permissions to write to the file because it belongs to root. Right?