Office XP is not supported on Windows 98, although in most cases most things work. There might be some particular cause for the behavior you observe, but it isn't clear from your description.
Without any details given (and most likely also with more details) the advice can only be:
Either install Office 97 or 2000 on Windows 98
Or install Office XP only on Windows XP
the installation of Office XP don't continue when it stop installing the system files update. what should i do?