I'm starting to have some problems with my iMac - does anyone recognize these symptom

[Aethon]

My iMac is doing some strange things since I updated the latest security updates to 10.6.8 in August 2012.

In the last couple weeks, the following things happen :
- during copies, the mac will freeze for a few minutes and then I get an error of -36
- out of nowhere the mac will just freeze, especially when iTunes is playing a song, so the song is interrupted several times
- folders are being affected without my touching them, as I see by the date modified
- loading a page in my browser seems slower now and there seems to be a pause between typing in a URL/hitting enter and seeing the page

What is going on with my iMac 2.4 GHz Intel Core 2 Duo?

If you guys have any ideas, I would much appreciate hearing from you.

Thanks!

 

[Dysfunction]

error -36 is an I/O error. Given the rest of your symptoms, I'd replace the hard drive.

 

[Aethon]

Thanks for your response, however...

Every time I run tests like S.M.A.R.T. status tests and Disk Utility there is no problem? This is why I think it's a software thing because it only happened after the last security update.

There were no problems at all until I did that. There was some issue when I did the software update so I had to reinstall it again from a file I downloaded from the apple site.