This issue is caused by having a Home view which is taking a long time to load and then is exceeding the hosted server load balancer time out, which gives the "Service Unavailable" error.
To see which Home view may be causing this. You will need to remove access to all of the home views, one by one, and get the user to log in each time. This will determine which Home view is causing the error.
Note: Make sure you make a note of what they are so you can put them back afterwards.
To remove a Home View to a user you must first ensure the users profile has access to it:
Log in to FocalPoint Administrator
Click System Control, Security Profiles
Select the relevant profile and click Edit
On the Home Views tab, ensure all required Home Views are in the right hand list.
To move one, select it and click Remove
Click OK to save all changes
The user will then need to follow the steps below to remove the Home View:
Log into the FocalPoint website
In the top right, click their name, Preferences
Under the Homepage section, there are 6 numbered drop-downs, use them to remove the required Home Views. The views will appear in the number order.
Click Save when they are happy with the changes.