Regarding the lockup when you log in?
What do you mean by lock up? Does it just hang? Are you able to log in but then there is no manager (blank screen), or there are parts of the manager, but perhaps some parts are missing... like the resource tree on the left, or the menu bar at the top?
There are many posts on forum regarding manager issues with 2.3.3 and manager issues. As far as I can tell, much of this has to do with the hosting. Shared hosting environments can be a bit dicey when it comes to MODx. MODx-friendly hosting is your best bet.
http://bobsguides.com/modx-friendly-hosts.html
Before switching hosting — first try to turn of the compress css and js in the system settings. If you are able to a least get logged in and get to the system settings, find compress_css and compress_js and change those values to "No". Then clear the cache using the menu item at the top Manage > Clear Cache.
If you simply are unable to log in and get to the system settings to make this change, you can change it in the database using phpMyAdmin. There is some info about doing this at Bob's Guides
http://bobsguides.com/modx-installation-faq.html See question third in the FAQ list:
I've upgraded MODx and the Manager is all messed up. What now?
Basically you log out and edit the modx_system_settings table in PhpMyAdmin. Find compress_js and change the value to 0,then delete the core/cache/system_settings/config.cache.php file and log back in.
I do this with both the css and js, though Bob is only recommending it for the js in this post.