Cope with NULL labels in every control where it makes sense, and assert that

[u/mdw/putty] / website.url

[InternetShortcut]\r
URL=http://www.chiark.greenend.org.uk/~sgtatham/putty/\r
\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0