Safari on iMac issues

I'm having a lot of issues only on my iMac with Safari loading webpages and .aspx type environments. Firefox will load them on the same computer, so I know the proper software/plugins are installed and they'll open on my PowerBook, so I know it's not the web sites. Is there any sort of reset for safari other than the Reset Safari option in the Safari menu? I've tried that and it didn't work. When trying to load a page (that I know it won't) there's no internet activity at all. I was going to reinstall safari but the installer said I needed to upgrade to 10.5 before using it, I'm using 10.6...
Any thoughts?