The problem has not descended into oblivion. I have a variation of it, with the difference that on loss my modem resets (didn't use to, I used to have a no sim icon).

It happens randomly but once it starts there is no return. The syslog is filled with CMT modem resets, from one every 5 minutes to 5 or more per minute until, at some poit, it just gives up and shuts down. Only removing the battery allows powerup.

Mine happens with infuriating regularity once I drive to and from home. Very odd.Still digging.

SIM_IND - default case, cause: 36

Jan 19 10:34:34 Nokia-N900 cellular: ssc[1064]: Unexpected modem reset, waiting for modem reboot
Jan 19 10:34:34 Nokia-N900 cellular: ssc[1064]: Starting cmt restart timeout
Jan 19 10:34:34 Nokia-N900 bluetoothd[1273]: get_operator_name failed with code 2
Jan 19 10:34:34 Nokia-N900 cellular: csd[1108]: com.nokia.csd.GPRS: Phonet up - activating
Jan 19 10:34:34 Nokia-N900 cellular: csd[1108]: com.nokia.phone.net: net_phonet_link_status: link UP
Jan 19 10:34:34 Nokia-N900 cellular: csd[1108]: com.nokia.phone.SIM: phonebook_phonet_link_status: link UP


then, after a while,

Jan 19 10:34:35 Nokia-N900 cellular: ssc[1064]: change to normal mode, ape ready, sim ready
Jan 19 10:34:35 Nokia-N900 cellular: ssc[1064]: change mode to MTC_NORMAL
Jan 1 00:00:03 Nokia-N900 syslogd 1.5.0#5maemo7+0m5: restart.

Sigh.