There is no problem with wp 3.4.2. I don't know how many million times it is been downloaded with no problems.
Actually it does here is one examplewp-admin.min.css doesn't exist in the new version of wordpress
http://www.ourexcellentadventures.com/wp-admin/css/wp-admin.min.css
and here is another example
http://techcrunch.com/wp-admin/css/wp-admin.min.css
The code being generated by your wp-admin is different than my code in a couple of places. For example your code shows <body class="login"> while mine shows <body class="login login-action-login">
I suggest you follow the standard debug for problems.
- deactivating all plugins to see if this resolves the problem. If this works, re-activate the plugins one by one until you find the problematic plugin(s).
- switching to the Twenty Eleven theme to rule out any theme-specific problems.
- resetting the plugins folder by FTP or PhpMyAdmin. Sometimes, an apparently inactive plugin can still cause problems.
- re-uploading all files & folders - except the wp-content folder - from a fresh download of WordPress.