[Skunkworks] Access denied on server 2003

Hi guys, I am working with win2003 as a server and several machines access files from this server. For along time i have been able to map a shared folder on client machines. but recently i have had a problem When i try to access this folder from a client machine - it asks me the user name and pswd and it connects, but when i map the folder and try to access it, i get an access denied error. I have tried mapping other folders on the server and they dont give me the error. Its only this one folder behaving this way. Other machines that had this folder mapped earlier on are just ok and allowing access. So am puzzled. What is wrong. any advice will be highly appreciated