This question has been answered by BobRay. See the first response.
@rrswans: You didn't mention running setup. That will usually (but not always) straighten out the paths for you.
Delete all the files in the core/cache directory and clear your browser cache and cookies after running setup.
If that doesn't work, it's time to check the 4 config files:
core/config/config.inc.php
config.core.php (in the MODX root)
/manager/config.core.php
/connectors/config.core.php
Also check the rewrite base in .htaccess if there is one.
If it can't connect to the database, either the database info in the config file is wrong or the user whose DB credentials you put in the config file doesn't have full rights to the database. Some hosts add a prefix to the database name. Check in PhpMyAdmin to see the true database name and make sure it matches the name in the config file.
Thank you!
Delete all the files in the core/cache directory and clear your browser cache and cookies after running setup.