If "a.txt" is a file freshly created with Hamster (this is essential to rule out any problems with permissions), then it leaves me stunned. The only thing that I can think of is some random corruption, possibly fixed by rebooting or reinstalling Hamster.
ls -la drwxr-xr-x 2 root root 4096 Dec 23 16:41 .myscripts sudo chown user .myscripts/ ls -la drwxr-xr-x 2 user root 4096 Dec 23 16:41 .myscripts sudo chgrp users .myscripts/ ls -la drwxr-xr-x 2 user users 4096 Dec 23 16:41 .myscripts