( and other logged in users) keep gettting the spinnging rainbow wheel.
When you have problems with Safari in multiple user accounts, that's an indication that the startup disk needs repairing.
Launch Disk Utility located in HD > Applications > Utilities
Select the startup disk on the left then select the First Aid tab.
Click Verify Disk (not Verify Disk Permissions)
If Disk Utility reports errors, with v10.8 Mountain Lion installed, the only way to repair the startup disk is to use OS X Recovery.