#10 External commands break 'set mouse=a'

[Anonymous]

I have 'set mouse=a' set in my .vimrc to allow me to click anywhere in a file. If I use an external command though, I can no longer click anywhere.
This happens both with typing a command (':! pdflatex %') or with a predefined shortcut (',p').
Trying ':set mouse=a' again does not work. If I want to keep clicking then I have to reopen the file.

I am using Arch Linux, kernel version 3.1.1, vim version 7.3.353.