To reset your device, switch off the car engine and then remove the memory card. Re-insert the memory card, wait 30 seconds and switch the car engine on again.
Sorry for confusion about firmware version. 8.843 was the last version for the Carminat. 9.884 was the last version for the Carminat Live, which after re-reading your original post, I see is the device you have.
I wonder ... it's been a very long time since we've seen one particular problem (we don't work with very many of the older Nav2 devices these days), but we used to see an errant QuickGPSFix file blow things up this way.
Place your Carminat card into your PC, navigate on the card to the folder called "ephem". Delete the content of that folder (not the folder itself), which should be 4 files.
On your PC, find the folder that Home uses for downloads. If your OS is fairly recent, this will be C:\Users\{your username}\TomTomUpgrade\HOME\Download
Within that, you will find a folder called ephemeris (or is it ephem? I forget). Whichever. Do not delete that folder, but delete all of the folders within it.
Now connect up with Home again and allow it to provide you with a current QuickGPSFix.
Does that help?