I had this problem with a V2 a mounth ago. All of sudden the config was defaulted and could not sent a new one in. Removed the SD card, deployed a config on the using a laptop and it booted up okey. After a reboot it was gone again and it went on and on the same way. Ended up replacing both the Sd card and the control unit.
This is an output from my trace at that point:
1625093mS PRN: Config Service: Erasing Config
1625424mS PRN: Config Service: End Write
1625430mS PRN: System Reboot (from 192.168.1.4).....
1627835mS PRN: SMXFS: Found invalid FAT node 0xFFFFFF8
1627836mS PRN: WARNING:
1627836mS PRN: OSBuffer::Length exceeded f61871a0 15500 (f047c264 f01d9504)
1627836mS PRN:
1627836mS PRN: BUF f61871a0 : data=f7d4701a , length = 20
1627836mS PRN: 0000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
1627836mS PRN: 0010 00 00 00 00 ....
1628205mS PRN: LoadCountControl: Marked As Successful Boot
********** contact lost with 192.168.1.96 at 11:33:08 9/4/2010 - reselect = 2 **********
******************************************************************
********** SysMonitor v8.0 (8) **********
********** contact made with 192.168.1.96 at 11:34:19 9/4/2010 **********
********** System (192.168.1.96) has been up and running for 36secs(36930mS) **********
********** Warning: TEXT File Logging selected **********
********** Warning: TEXT Logging to File STOPPED on 9/4/2010 11:34:19 **********
36931mS PRN: Monitor Started IP=192.168.1.4 IP 500 V2 6.0(8) 00E007056104
(IP Office: Supports Unicode, System Locale is default)
36931mS PRN: LAW=A PRI=2, BRI=0, ALOG=0, ADSL=0 VCOMP=32, MDM=0, WAN=0, MODU=0 LANM=0 CkSRC=0 VMAIL=0(VER=2 TYP=3) CALLS=0(TOT=0)
38057mS PRN: Check for duplicates took 0 ms
38057mS PRN: Sorting Directory List...
38057mS PRN: Sorted Directory List.
38058mS PRN: Config Write Completed