Do you have Gigabit devices at both ends? If so, Cat5 just won't do the trick. As Dot said, 100 m/300 ft is the maximum length between two devices, which you haven't exceeded. But as just was testified in another thread, Cat5 and gigabit cards don't mix. You should have at least Cat5e, rather Cat6 cabling for the newish connections to work. I believe that the short cable you used in the server room is either Cat5e or Cat6...