HELP Latitude network problem Can not share files

I have a small network with 5 computers,  and have used microsoft office to set up,  all of the computers, are connected to the net by a linksys ap/router to dsl modem,  all computers can go to the net,  All computers were set up with microsoft office from a floopy from one computer to another,  all computers have the same workgroup name,  all of the computers show up on my network except for the dell.  The dell shows up on all of the computers in the net work but will not share files, you get a message to contact adminstrator?  Only the Dell shows up on on the dell under my network places... none of the other computers,  I can not seem to find any direction to fix this problem,  can any one help me out,   Thanks  Ron