Apple Mac Pro Desktop Computer Workstation (Early 2009) (Z0G100026) Mac Desktop "start rainbow" Questions

...rainbow wheel again, permanently. This seems to happening a lot at the moment! From experience it can be a number of things, the worst being a failing hard-drive These imacs are now at least 6 years ...

...start up, it'll hang....ill see the flashing folder icon or apple logo. If I hold down the option key I can usually get to the desktop. It may work for a short while then freeze again. The spinning ...

...rainbow wheel and crunching the spinning wheel and crunching will last for long periods of time which is annoying. This only happens while on the internet. When it does stop crunching it will start ...