I've researched this problem and I've made some changes, but still my old iMac, yes old, has lately been taking a long time to start and shut down. I sit and watch the circular icon. Possibly I've also been getting the beach ball in the Finder more than I used to.

I have reset the PRAM, SMC, deleted unnecessary files, disabled login items, run the Onyx options, used Disk Utility, reinstalled OS 10.6.7, disabled and deleted fonts, stripped languages and architectures with Monolingual. I even disabled Dasboard via sudo, which did nothing. My hard drive has a 160 GB capacity and I've used almost 60 GB of it. That might be the most telling item, but there's a still a lot of space.

Helpful suggestions are welcome. Thanks.