We had these problem for several chips. Sometimes the firmware is gone that we had to reinstall framework and our software, sometimes the data in flash disappears when power is shutdown.
Does anyone have such issues before?
I’ve experienced something like that once or twice. An EMX just stoppped working one day until I reflashed it. Cosmic rays? 
I think if you look around the forum there are some threads on issues with data on flash. But also make sure after making changes that you call Util.FlushExtendedWeakReferences()
As for the framework and software disappearing, we have experienced this. Take a look at this thread: https://www.ghielectronics.com/community/forum/topic?id=12409&page=1
At the minute our work around is to basically toggle LMODE OFF and ON until we upgrade all are client applications to 4.2.
This may not be your issue but sure give it a try and see.
@ Chris_MC -
no, there are two issues:
- we do use FlushExtendedWeakReferences to flush data into flash, but somehow we still lose data after re-powering the device for a few times
- we lose all the firmware. after re-powering the device, we found the firmware is gone from COM1 port.
Are you using an external voltage monitor IC ?
I had this problem in the past, but with a different MCU (an MCU with internal flash).
The solution was to add an external voltage monitor IC + after each flash write to change the flash address pointer to the last flash address. This way if any spurious write happen they will corrupt an unused flash sector.
This is my 2 cents.
Good luck, from first hand experience I know these complete system failures are frustrating.
S.B.D
@ S.B.D. - I had same kind of problem however with a G120 module. Re-flashing just config.hex brought the device back to live. The managed app and clr was still working. Why the flash gets corrupted is still an open question.
@ RobvanSchelven,
Is your EMX module also running networking tasks as the G120?
I’m following your G120 thread with great concern as I am building a custom board with the G120 - no networking at all in my case though.
S.B.D
@ S.B.D. - I am just using G120, No EMX.
@ RobvanSchelven - of this happens again, please enter tinybooter and load the config file only and tell us if this fixes it. We are trying to determine if this is a firmware corruption or it is config.
@ Gus - I guess you mean @ S.B.D. 
To anyone with similar issue.
I too just experienced this anomaly this week… My app running on a the original Cobra .NETMF v4.1 all of a sudden went away. It took awhile to figure out how to get the system back because every time I powered the system up it would start to boot and then go to a blank screen just like I was resetting the unit to get to the boot loader. It wasn’t until I got it to boot to a place where I could erase my app and it behaved properly. I’ve reloaded my app and it has been running without issue.