iMac sucking lately

Hey everyone,
Yeah as the title says my iMac is not running the way it should lately. I have the 17 inch 1.83ghz intel processor with osx 10.4.7. Here are some of the problems.

1. I will be using it for a little while (haven't got an exact time) and I won't be able to go to the bottom right corner to bring up all my programs open or get my dock to display. I tried opening up system preferences to play around with and it won't open. I have to restart the computer to get it working properly.

2. When I go to shut down sometimes the computer will not shut down. It will sit there and then go to sleep.

I really have started to get annoyed with the intel line of macs. I didn't have nearly as many problems out of my g3 ibook. I understand these things will have bugs and get better though. Thanks.
Josh

Doesn't sound like a bug to me, sounds more like some form of hardware issue, I've never seen this behaviour on my iMac... anyone else?

Well I think I figured it out. I had the background that was the alternating pictures and the screensaver that was the changing itunes cd covers. Well I changed them and now have not had the problem. Very weird.

Interesting, could you perhaps have some corrupted image files that are causing the lock ups when they try to display? I just use the image slideshow screensaver using my iPhoto library but never seen the problem, maybe try removing one of these things at a time to try and isolate it better?

Yeah all I had were pictures of the logos of all my favorite teams sliding in the background. Oh well it works like a champ now so I'm all good. Thanks for the input.