When certain users log in to the instance the homepage being used does not load properly and instead keeps on reloading.
The affected user(s) is using a homepage that is set for another user erroneously.
1) Identify the current homepage that the affected user is using by navigating:
User Administration > User Preferences > Find the record where Name = homepage, User = the affected user
2) Under the Value field either blank out this value or replace it with another sys_id value from the sys_portal table (the table that stores homepages) that the user has access to.