SD error 0XA and 0X1 when changing to net supply

Hi all,

I use the SdFat library.

I log data from 8 accelerometers at 50 hz on a SD card. While this works fine when the arduino is fed trough power supply instead of USB, the sd card module stops working. It states

Can't access SD card. Do not reformat.
SD errorCode: 0XA

This typically happens when i first power on USB, then (while running) plug the net supply and press reset.

Sometimes the reported code is 0X1. I cannot reproduce when this happens exactly.

I read in another post that this could be due to power issues: Arduino Forum

Since i change the power supply it seems most likely that this is the source of my problem.

What can i do to fix this?

EDIT: i think i need this: Electronic Equiptment - DIY LM317 power supply Please confirm!

Thank you

my adapter: