I upgraded my Mac Mini well over a month ago, maybe two months ago, put a bigger hard drive and more RAM in it, got the RAM of crucial, following their system tool. I have had no problems with it for the first month at all and my system is much quicker too.
I only mention this as this is the only thing I can think of which has changed.
Any ways, over the last few days my system seems to become unresponsive, although I can still move the mouse pointer around the screen. If I hold the power button for several seconds to do what I think must be a cold boot, the system does boot as normal, but seems to take a few minutes longer than usual, I think.
Anyways, after I've started an application or two, no matter how long I leave it after booting up, the system becomes unresponsive, but as I say I'm able to move the mouse pointer.
I did think the other day that the system was running a little hot, but last night when it became unresponsive, it wasn't hot at all.
I ran the disk permission repair tool a couple of days ago and it did fix things, but the problem remains.
How can I diagnose my problem? I'm pretty sure I'm out of my Apple warranty, my Mac mini is a 2009 model, also I've upgraded it, hence breaking my warranty I think. FYI it running Snow Leopard.