Shortcut key assignments in Word 2003

The company I work for is changing to a new platform (their own creation)and I am having problems with placing bookmarks to mark questions or blanks. I use Word 2003 and when I do a list of word commands it shows "Ctrl+Shift+F5" to insert a bookmark. The new platform told me to use "Ctrl+Shift+G" to insert a bookmark. When I looked up the Word List Commands on my computer it gives "Ctrl+Shift+G" as a shortcut for word count list. Sometimes their way will work perfectly and sometimes it will not and a "Word has encountered a problem and needs to close..." comes up and then tries to recover the document and I lose my document. It is very frustrating. I have tried to reassign the command but am unable to find an "insert" - "bookmark" in the keyboard reassignment. I would appreciate any ideas and help.