Your css sytlesheet, collapse-close.css, contains a .close element that is bleeding into the admin page and is being shown on the Close button of the new Feature Pointers in version 3.3.
Here is how to fix it (from http://wordpress.org/support/topic/troubleshooting-wordpress-33-master-list):
2. CSS ISSUES. The second problem is related to plugin styles (or theme
styles) bleeding into the admin.
- The symptom. Something doesn't look right in the admin, typically on the
dashboard, comments screen, or post/page edit screen (post-new or post.php).
- To confirm: Some CSS file from some plugin or theme is being enqueued
when it shouldn't be. This is visible in the source in the admin.
- The fix: It'll be fixed in WordPress 3.3.1 (timeline still TBD), but for
now, you can use Hotfix 0.8. Hotfix 0.8 will remove all styles accidentally
enqueued in the admin.
- The better fix: One of their plugins is guilty of using the wrong hook.
There's a bit of nuance here, but I've posted a summary at