I have a 3 cabinet XTS 3.0 system. The 2nd cabinet has all slots filled with SLIBC cards. On a random basis, a port will lock up until I power cycle the 2nd cabinet. It isn't always the same port or the same card. I've tried cleaning all the contacts on all of the cards. The 1st cabinet has 2 SLIBC cards and the 3rd cabinet has 4 SLIBC cards. No problems with any of those. Voltages "look" on all the cabinets. What could be causing this problem in the 2nd cabinet?