In that case, I don't see how it could be a memory leak. Indeed, it sounds like a hardware issue, though I have no suggestions as to specifics of the problem or a solution to it.

What kills me though is that it has happened to BOTH phones I have purchased. I purchased both from Nokia. So this makes me think it is an issue from my side: ie an app (since i always restore the same apps) is causing this issue, maybe an app that loads everytime the phone turns on. Or maybe the SIM, or the SD card. The interval of options is very very wide, and I am kind of upset with that. Hopefully we will figure it out. Thanks for your help!

You can reset the gsm modem without rebooting n900. It's very hit and miss, because you're doing it behind the back of the software on the omap3, and it's pure chance that determines whether you timed the reset so that the software tries to restart the modem...

I did this for a few weeks, having my reset line cycling line of commands ready, and pressing uparrow enter repeatedly hoping to hit the right timimg, and that I wasn't holding my n900 in the postion/way that made it go to crossed out sim in first place...

I get this error when i flash my n900 using global firmware.
I am living in India and my n900 shows sim card error if I flash any other firmware except for indian version.

is anybody that installed a different type of software on their n900, to see if the no sim issue is going away ?i am about 80% sure that is a soft related problem. this is because imei is gone when the problem occurs. i did take apart the n900 a dozen of times for different reasons, and it has nothing to do with the hardware , as far as bad contacts.
other issue that i am trying to figure out is how the problem occur?
it seams hard for me to remember right , but i think it happen as a result of installing an app
i wonder why the software updater is not available anymore....to reinstall the soft ...i did found i,t on cnet, but after it did an upgrade ...it turn to be in spanish...witch means different region...also..when i did installed fresh from cnet, eng version...when connecting the n900, the soft was having an aware sign, that the time on the n900 and the computer was not the same...even when it was the same...after the update of nokia updater, the software is in spanish, but there is no aware sign for not match time.

The paper in between battery and sim solved for me..
I think it is loose soldering or dry solder on the sim slot as suspected by joerg_rw. in the post here http://talk.maemo.org/showpost.php?p...4&postcount=31

Also, I had this problem consistently after i changed to a new original nokia battery.. maybe the old one had swollen and applied pressure to the sim slot.. The new one created a palpable gap..

As of now i also have tried pulling up the data points on the main board where the GSM antenna connects, Wiping them with alcohol, slightly bending sim slot pins, Only the paper seems to work..

I have this issue since Sunday, paper doesn't work for me, although I will be trying a full reflash tonight (my first one in 20+ months!!)

One thing I did notice is that the tablet mode/phone mode option is no longer available from the power menu. I was hoping to leave it in tablet mode so I could use WiFi only, but no joy. The "cell-modem-ui" application is still installed, and as far as I recall I did not install anything new to make this problem start, making me think it is hardware related...

@JohnLF,

Please post the output of 'ls -l /etc/systemui'

It should contain a file called 'cell-modem-ui.xml', or a symlink to a file with that name on /opt/cell-modem-ui.

Very weird. I swapped phones for a day then took it into the shop I bought it from to show them the error (I still have 3 months of contract warranty left). I put the SIM back in it and of course it didn't fail. It's been working perfectly since...including having tablet mode back on the power menu. If it goes again I will do the commands and post the output.

FWIW, I've had the sim icon dissapear a couple of times on my phone, it started after I'd dissasembled the phone to fit a new LCD - I never comlpeted that because I stripped one of the P00 screws without getting it out, so I just reassembled everything without swapping (I didn't even have a replacement LCD ready to swap when I did this, I was just doing a dry run before buying one).

Anyway, I'd exerted a LOT of downforce when trying to remove those pesky screws, and once I reassembled it all I immediately got the SIM missing icon. I first powered down, removed SIM, claned it and reinserted - no joy.

I then took it apart again and reseated the cable that connects the two main parts together. Once I'd done that and reassembled it again, the ketboard slider was no longer a flush fit - the gap at the front edge is a bit wider than it should be and the keyboard LED's are slightly visible when the k/b is open and you peer into the gap. I know that's because I didn't position things perfectly when reassembling, but as my SIM now worked again I didn't risk yet another dissasembly and I've just left it at that.

I have had the no SIM icon appear again twice since (over a period of about 3 months). Both times have been since I bought a second battery, such that I now open the phone to swap batteries occasionally. The fault happened once immediately after a battery swap and the other time just randomly while the phone was in normal use.

Each time, just removing the SIM, cleaning & reseating it has done the trick, but my own suspicion is that I have probably cracked a solder joint or a conductive track near the SIM tray on the main PCB on my original disassembly, and that flexing the N900 can occasionally cause that crack or joint to go faulty.

Just a guess, but has everyone who experiences this problem dissassembled their phone at some time PRIOR to it first occurring, and did you all have to use a lot of force when removing/replacing the screws?