Sorry, my eyes must be blurry, too much computer work today.
But can you tell me where you have set the pinMode to be 53 other that 10 or where you have mentioned it?
When I look in you code section I am sure I see the following
Serial.print("Initializing SD card...");
// make sure that the default chip select pin is set to
// output, even if you don't use it:
pinMode(10, OUTPUT);
I guess with that last comment of yours, you are welcome, I shall leave you to it then.
rockwallaby . .