Hi this is just to help anyone if it happens to them. My husbands SP had a message saying "system UI not working" sent to Sony who repaired it came back put sim and SD card in same message came up called Sony back yesterday about phone still not working and nice gentleman went through all setting nothing could still be done with phone. He sent some info by email to try and said he'd call back today. Spoke to my son who lives away explained to him he said try taking sim and SD out and try them one at a time turned out the SD card had become corrupted. So lot of apologies to Sony but none of the advisors I spoke to had heard of the UI system failure before so it will be a learning curve for them also. Sorry this has been long winded but I thought it may help someone else.
