There seems to be a data corruption problem in the folder of the application, we don't know the cause of this corruption (maybe a crash or a problem with your device).
Can you please stop the application, completely delete the "geolives" folder from your device and launch the application again? It should fix your problem.
Warning : You will lose all the trails you have not yet sent to the server, so please send the trails you need to backup to the server before doing this operation.
After that, you can download your maps and your trails again.
Sorry for any inconvenient caused.
Files with numeric names are files of recorded or downloaded trails.