Office2k cant see directory explorer can

We have a Unisys NX4600 Mainframe whose drives look link any other NT server to the network. We recently installed Windows2000 and office2000 on some PC’s and in Office2000 you can not see the file directory. Using explore you can see it and even copy the file local where you can then use it. NT40/office2000 does not have this issue. Why would explore work differently than Word or Excel for file browsing in W2K?