This indicates a HW error with your switch.  If you are still under maintenance, call Dell support.
I'm new to managed switches so I picked one up for learning. It didn't take long before encountering problems. From the console I encountered a "failed" message after "loading startup configuration" and switch rebooted (looped).  The SW version was old and since I could not get to the CLI prompt used XMODEM and loaded latest version, 2.0.0.36. Could not figure out how to load boot software without CLI and thus remained at 1.0.0.6, 9-OCT-2007.  Things got better but only a little. Now the system hangs at "Unit Standalone" The following output appears. Running From RAM Running SW Version 2.0.0.36 Date 23-March-2009 Time 16:19:23 HW Version 00.00.02 Base MAC 00:21:9b:b5:0f:b3 Device Configuraton: Slot 1 - Ethernet Switch Unit Standalone No further output - hangs. I tried erasing the configuration file "config" but nothing changed. Any help or suggestions is appriciated. Thanks.  
Powerconnect 5424 Hangs