This is really strange and i would like to solve it.
My Macbook Air works fine all week, but EVERY Saturday morning, when i first open it to use it, after about 2 minutes it starts freezing and getting the spinning rainbow thingy. This lasts about 1 or 2 minutes and keeps repeating itself for around 20 minutes or so.
After that its fine and no longer does the spinning rainbow or freezing or anything.
This ONLY happens on Saturday mornings.
Restarting is useless. I had even re-installed OSX and it still remained the same.
I tried loading Console, but nothing strange was reported.
The computer is a MacBookAir2,1 with 120GB HD, 2GB DDR3 and Mac OS X 10.5.8 Leopard.
It sounds like you have a backup program, or other progam that is trying to do something scheduled. When it does that, have you looked at the Activity Monitor to see what is running, whether a program is monopolizing the CPU? Activity Monitor is under applications/utilities.