I traced the error message to the php function 'is_readable', which is returning false. In moodle/lib/moodlelib.php, ‘moodle_needs_upgrading()’ runs is_readable on each module’s
version.php. In this case, moodle/mod/lamstwo/version.php.
Perhaps some other app has a lock on it (even though theoretically it should still be able to be read). The only thing similar to this that I’ve come across is when I want to open one of jboss’ log files in Windows using Wordpad, and Wordpad will complain saying the file is in use. Is it possible that you've got lamstwo's version.php open in an editor?
Another (remote) possibility is a bug in the PHP function similar to the one reported here http://bugs.php.net/bug.php?id=30931. But if this were the case there'd probably be more errors.
Did you manage to install the lamstwo tables by accessing http://moodle server/moodle/admin/? It should show up in the modules listing after that.
Posted by Jun-Dir Liew