the low memory error is due to no swap. The good news is you just might have wrongly partitioned or corrupt eMMC. The bad news is it may be a hardware fault of the emmc. Try a full reflash as per the wiki becsuse without swap the device is pretty unusable anyway so it eill be a PITA to try and fix it via xterm. On the other hand if you really want to give it a shot, install ssh, reboot and connect to the N900 before you open any other application. Then check /etc/fstab for the lines that correspond to MyDocs and swap.