Today, I pulled down the laravel/laravel repository from Github. I then ran php composer.phar install (as I normally would on my system, with a command window in the project directory). However, when I ran php composer.phar update, I received this error:

Everything installed just fine, and Laravel works as it should.
Any ideas what could be causing this issue?
Edit 1
artisan exists in the root of the project, but it throws an exception when I attempt to run php artisan optimize:

Side Note 1
If I try the alternative method (quicker) of installing Laravel (php composer.phar create-project laravel/laravel), I get the following:

Edit 2
Upon installation, I also get the same error, where it claims it cannot find artisan. Therefore, the installation does not fully complete. I believe that it is stopping when it wants to compile classes (or something to that effect), and then write bootstrap/compiled.php. That file doesn't exist.
Here's the snap from the install:

Edit 3
It seems that Composer is looking for artisan in the drive root (C:\). Why is it doing this? Even if I specify -d on the update, it throws the error. (I picked this up from a hunch - simply copied artisan to the root of the drive and it found it - albeit, it obviously did not run...)