vim should complain if $SHELL is not set (and therefore "shell" in vim). "!something" won't work without it. Reproducible: Always Steps to Reproduce: 1. Login as a normal user 2. "su" to root 3. Start screen 4. On my computer, $SHELL is now empty (have to fix that anyway) 5. Start vim
In 6.3.084-r1, thanks.
This has been fixed in Vim 7.