On the final steps of the installation, the CSS files relative paths are wrong.
<link rel="stylesheet" type="text/css" href="style/Oxygen/Oxygen.css" />
<link rel="stylesheet" type="text/css" href="style/Oxygen/Oxygen_forms.css" />
<link rel="stylesheet" type="text/css" href="style/Oxygen/Oxygen_cs.css" />
<!--[if lte IE 7]><link rel="stylesheet" type="text/css" href="style/Oxygen/Oxygen_ie.css" /><![endif]-->
"../" Should be added to each one of them.
Edit: Actually, should be replaced by: [Lines 1777-1780 on 'admin/install.php']
<link rel="stylesheet" type="text/css" href="<?php echo FORUM_ROOT ?>style/Oxygen/Oxygen.css" />
<link rel="stylesheet" type="text/css" href="<?php echo FORUM_ROOT ?>style/Oxygen/Oxygen_cs.css" />
<!--[if lte IE 6]><link rel="stylesheet" type="text/css" href="<?php echo FORUM_ROOT ?>style/Oxygen/Oxygen_ie6.css" /><![endif]-->
<!--[if IE 7]><link rel="stylesheet" type="text/css" href="<?php echo FORUM_ROOT ?>style/Oxygen/Oxygen_ie7.css" /><![endif]-->
Edit: 'lang/English/admin_common.php' and 'lang/English/admin_ban.php' are missing?
Edit:
Notice: Use of undefined constant FORUM_MAX_POSTSIZE - assumed 'FORUM_MAX_POSTSIZE' in Z:\repository\punbb_rc2\lang\English\misc.php on line 14
when viewing 'moderate.php?get_host=127.0.0.1'.