gcd(0x2200,0x7800) = 512

So some part of the chain with 512 byte buffer size corrupted the data.

It doesn't look like a memory corruption but if this were my computer I'd run the equivalent of memtest86 on it.

It looks like a filing system corruption to me. Running `diskutil info` on the main harddisk and the sd card might be interesting to see if the block sizes match.

Running a disk tester on the sd card and the main disk might be a good idea too. Here is one I wrote: https://github.com/ncw/stressdisk