domain shares issue

hey dudes

the problem im sittin with is poppin up on a few pcs now that has never been a problem before. mapped drives are not showin any of the data, certain mapped drives only show 1 folder. they all used to be fine before. for instance i hav a printer shared from the server, if its connected by \\servername its sometimes disapears, if its connected by \\ipaddres then its fine! and the same applies for my mapped drives, if its connected on servername it givs problems, and if its connected via ipaddres then no problems at all. please can someone help me on this 1.