Hi Sungjin,
This looks like there were problems writing the previous files. Plus, the latest "Cannot allocate memory" error suggests you still do not have enough RAM. That is also why your computer starts getting very slow. The RAM is probably not bad, it is just swapping memory because it is running out, which makes everything much slower.
It would be nice to include output from the commands that I mentioned, which might get expanded a bit:
ls -lh pb0*BRIK*
3dinfo -n4 -datum -prefix pb05.*.r01.scale+tlrc.HEAD
3dinfo pb05.*.r01.scale+tlrc.HEAD | head -n 30
free -h
That this produces 160 GB of output suggests these are large datasets.
- rick