Question : Gb Network Issue

I recently upgraded all of our backbone to a Gb network with fiber uplinks.  All is well for the exception of a couple of users/computers have really slow connections.  Specifically, 1 PC has a Gb connection and the other has 100Mb and both have the same problem.  I have tried changing the speeds, taking off auto (negotiation), checking the physical connection, etc. I am out of answers.  Their connection is there but its terrible.  I am using 3 Dell power connect 2824s and 2 5448s, the problem seems to be stemming from one of the 2824s on the first floor.  I haven't adjusted ANY settings on the switches out of the box.  Everything is pretty much wide open.  Any ideas?

Answer : Gb Network Issue

Poor cable plant. Gigabit speed is very sensitive to strict CAT5/CAT5e standards.