Share Folder

I have a folder in windows 2000 that has been shared to user using xp prof and win 98. The problem is when win98 user try to open excel file and other user xp try to open same file it give the message “read only click to continue” that message is fine, but win98 user saves that particular file unable to save file it takes ages to save it as becuase of user xp has opened it, is there any thing wrong with windows 2000 where the original file is there or problem with xp/98, before both user was using win98 and there was not even a single problem, please help me in this situation, my manager wants me to sought this problem very soon. AS becuase all the directors are using.