Problems mapping a drive to the IFS

I do not think this is an iSeries issue but we have exhausted the things we know to try on the Windows side of this. We have some folders in the IFS that we allow users to do drive mapping to using NetServer. The NetServer name is as400pct. We have multiple DNS names all pointing to the same IP address on the iSeries. Doing a drive map to some of these names works but for one I does not . We can map to the name of the NetServer (e.g. Netserver\Shares) we can map to DNS names (e.g. DNS1.pct.edu\Shares and DNS2.pct.edu\Shares but DNS3.pct.edu\Shares does not work for everyone but does work for some. For those that it does not work for if they go to a different PC it works as their userid. If we take the PC out of the windows domain all the names work the same. Put the PC back in the domain and all work but one. Our Windows team says it's an iSeries issue for IBM to fix. The iSeries team says it can't be because a PC not in the domain works it's only when it's in the domain that it does not. Has anyone ever seen this and could it be an iSeries issue? iSeries userids are not getting disabled for NetServer and if they were that user could not connect from any PC but they can connect from one and not another.