I would also reseat the stacking cables maybe even swap them around and if we see another reboot with the same errors we know it'snot the cables. I would also check the firwmare, I would verify that the switch is running version 3.3.1.10.
Our stack rebooted this morning. Can someone explain why? Error log below. 317     Warning     NOV 05 10:38:09     UNITMGR     Warm Auto-Restart complete on unit 1318     Info     NOV 05 10:38:09     CKPT     New backup manager selected, unit 2.319     Error     NOV 05 10:38:27     DRIVER     ATP: TX timeout, seq 0. cli 1. to 2(mac 0:25:64:1c:82:c3) tx cnt 21.320     Error     NOV 05 10:38:27     DRIVER     disc ERR: Operation timed out (-9) Failed to tx cfg pkt to 82:c3321     Error     NOV 05 10:38:29     DRIVER     ATP: TX timeout, seq 0. cli 1. to 2(mac 0:25:64:1c:82:c3) tx cnt 21.322     Error     NOV 05 10:38:29     DRIVER     disc ERR: Operation timed out (-9) Failed to tx cfg pkt to 82:c3323     Warning     NOV 05 10:38:30     CKPT     Checkpoint operation to backup unit 2 complete.324     Notice     NOV 05 10:38:30     TRAPMGR     Spanning Tree Topology Change: 0, Unit: 1325     Info     NOV 05 10:38:40     UNITMGR     Copy of running configuration to backup unit complete326     Notice     NOV 05 10:38:58     TRAPMGR     Stack Port Link Up: Index: 101 Unit: 1 Tag: xg2327     Notice     NOV 05 10:38:58     TRAPMGR     Stack Port Link Up: Index: 201 Unit: 2 Tag: xg2328     Notice     NOV 05 10:39:01     TRAPMGR     Cold Start: Unit: 0329     Notice     NOV 05 10:39:02     TRAPMGR     Stack Master unit 3 is failed330     Notice     NOV 05 10:39:02     TRAPMGR     Unit 3 is added to the stack331     Notice     NOV 05 10:39:02     TRAPMGR     Unit 1 identified a link failure in the stack. xg2332     Notice     NOV 05 10:39:02     TRAPMGR     Unit 2 identified a link failure in the stack. xg2
PowerConnect 6248 Stack Rebooting