OK, I know this is long, bear with me
I may have everyone topped here...
I upgraded Safari fairly soon after it was offered. I have a few Macs, one of which is a G5 iMac - the rest are Intel-based.
Around the same time (my recollection is fuzzy, bear with me), there was also a security update and a Java update.
In any case, shortly after I upgraded Safari on my G5 iMac, my web experience started to decline. Nothing horrible at first, slow-loading pages and such. Since I don't use that iMac a whole lot any more, no big deal, I didn't do any troubleshooting.
But over a couple of weeks, things just got worse and worse. I did the usual resets/reboots and such, no improvement. Then Mail started to not be able to connect, so I suspected my WiFi connection had gone bad somehow (new interference, what have you). So I started to troubleshoot that, and yeah, it kinda does seem probable that something's amiss there, I can't reliably ping my server, and pinging my DNS servers is problematic as well.
So, I did the usual and changed channels, moved antennas around, etc. No improvement. But I do see that now my signal strength is showing real low even after I put the changes back, and it won't even connect quite frequently. So, now I start to suspect bad WiFi hardware.
Around this time, I stumbled upon some of the threads talking about Safari 5 and networking issues. Even though it didn't make sense to me, I changed my DNS settings to the OpenDNS ones to see if that would help. As I expected, it didn't help - I couldn't even ping things locally. So, that was a red herring for my situation, confirmed by the fact that I didn't have any DNS lookup issues on my other machines (Mac and Windows). But the complaints did sensitize me to the possibility that this was a software-induced situation.
Next step was to take WiFi out of the loop and connect straight to my router using a cable. Doing this showed me that the problem was actually hardware, as I didn't get a link light on the router. Ahhh... bad hardware after all, right? At this point, I'm guessing that the WiFI and and the Ethernet are married on some daughterboard or something like that, and I'll need to replace that somehow (as an aside, how useless are computers now that can't network?).
Then I remember that I have a WiFi USB dongle. I check for Mac OS X drivers, yep they exist so I go download those on another Mac and get them installed on the G5 iMac. Well, the drivers are just for the radio side and I struggle to get the radio link up and running, but I do. Then, I need to configure the new en3 port (it shows up as Ethernet, can't show up as Airport of course) to get the DHCP, DNS and such. A couple of aborted attempts later, and I can see the assigned address pop up, and I know it's made a connection.
Success, right?
Nope. I still can't connect to anything. I can't ping reliably, either locally on my network or out on the Internet. Basically, even after installing new networking hardware, I still have the same exact symptoms as before.
It's at this point when I decide that I might as well do my first Time Machine restore. I pick a date far enough back where I know Safari 5 wasn't offered, and the security update wasn't there either.
After the restore, everything works just fine. AirPort WiFi is back to being solid as a rock, and the wired part works as well, and yep, the link light works now too.
Unfortunately, I can't say that this proves Safari 5 was the culprit, but it would tend to appear that way. But what Apple could have stuck in there to make the networking decline into a state where it made hardware behave so badly as to look broken, I don't know.
Yeah, I know "Cool Story Bro" but thought it might be helpful to someone out there.
