Doug, I understand how it has worked up to this time, but at some point, new hardware and software will likely not work correctly with older software/hardware. In your case, I do not think that it is a hardware issue, but rather a software issue.
First thing to do is upgrade your browser. You can either upgrade Safari or download and install Firefox. I personally would steer clear of Chrome for reasons unrelated to what's going on here. To give you an idea, the current version of Safari is 5.x, so if your version actually is what you say it is above, then you have some catching up to do. Assuming you have the inclination to stay with Safari, you may have to update it and restart your computer several times over to get it up to the current version supported by your OS. In other words, update Safari, restart your computer after the update is complete, and then update again (and keep going until there are no more updates available for Safari. Then, start updating programs potentially related to web-performance. Anything java, iTunes, security patches, and Quicktime come to mind. Some of these are going to take awhile and like the Safari update, you will likely have to download/install the update, restart your computer, and then check for more updates.
Without being there to see for myself, I cannot say for sure, but I honestly think there is a good chance that this will solve your computer issues. Also, when you go to do the updates, target specific updates rather than just do everything all in bulk. I have found that if you try to do too many updates at once, it can sometimes...for lack of a better word..."overwhelm" the system on a re-boot and some programs won't install or start-up properly.
I will also PM you my TX and if you want, we can chat tomorrow by phone. I want to be in front of my computer so I can better help if it gets to that point.