This is *NOT* something that just happens with one script, I have tested it on a couple (The add mesh ANT Landscape, the Dynamic Spacebar Menu, Add Masonry from contrib, and add mesh 3d function surface)

Whenever I try to install a new add-on and select the script in the file browser, the script is deleted (after I leave the file browser), which then causes the following error:

Traceback (most recent call last):
File "/home/jonathan/programming/blender-src/install/linux2/2.56/scripts/ui/space_userpref.py", line 1243, in execute
shutil.copyfile(pyfile, path_dest)
File "/home/jonathan/programming/blender-src/install/linux2/2.56/python/lib/python3.1/shutil.py", line 66, in copyfile
fsrc = open(src, 'rb')
IOError: [Errno 2] No such file or directory: '/home/jonathan/programming/blender-src/install/linux2/2.56/scripts/addons/add_mesh_3d_function_surface.py'

This happens both when I try to install an add-on that is already there (AKA reinstall), and also when I try to add an add-on that is not already there (the one I tried was the masonry script from contrib). For all of these tests, the script was deleted (On the hard drive, not just in Blender) as soon as I selected it to install and pressed enter.

r34860
Linux Ubuntu 10.04