Just upgraded from OS 10.3.9 to 10.4: Safari problems

Question

I just upgraded from Mac OS 10.3.9 to Tiger 10.4; everything is working fine, except as follows:
1. Software Update does not work. It seems that it tries to connect to the Apple servers (I can see the router and modem lights blinking), but a connection does not take place (the lights blink a couple of times every few seconds).
2. Safari connects without any problems to this and other Apple Support forums, but not to any of the bookmarks in the Bookmarks menu.
Also, I believe that I may have caused the problem, and will give the details hoping that my problems with Safari may help others solve theirs. I may have made a mistake right after "upgrading" to OS 10.4, specifically after the required restart.
When my iMac G5 restarted, a registration form showed on the screen. The form was the data on my account. My account is not an Administrator account, but a "User" account instead. There was an option to change the account's "User's name," so I went ahead and slightly changed it by adding a "dot" to my first name initial (I don't use my first name, just my initial).
-The old account name was as follows: R
-So I changed the account name by adding a "dot" (.) right after the initial, to look as follows: R.
Right after making the change, I had the option to immediately connect to Apple and REGISTER, however, a connection could not be established or the computer was not responding, so I clicked on "Register Later" and quit.
Mail works fine, and so the DSL modem and router. I can access this forum, but Safari tries but can't to connect to other forums.
Do you think that by changing the User Account's name I may have screwed things up? I have tried MS's Explorer, but it too shows the same problems.
Any ideas on what to do at this point?

Answer 1

Steven: I know that the problems I had with Safari is not similar to yours, but I ended erasing the hard drive and reinstalling Tiger four times (I have posted the full story in a couple of Apple forums).
On the pre-final try i removed the router from the computer and only used the DSL modem. However, I decided to use Safari between Software updates, and again Safari stopped working, as well as Software Update. I had removed every USB and Firewire cable, set-up the network to stay active without interruptions, set the computer to stay awake forever, the screen to stay awake for over three hours, and the hard drive to stay awake.
Then on the final erasing/installing, I made sure that I didn't use Safari until every little update was finished all the way to a complete Mac OS 10.4.2. Once that was accomplished I used Safari, and I have been using it since.
A friend of mine is upgrading the router's firmware, just in case that was par t of the problem, but I don't think it was, since the router was out of the picture on the pre-final session.
I believe that for some reason OS 10.4 screwed the Network panel functions. If you just look at the settings they seem to be OK, but not really. The problem may be related to the G5 CPU and how Mac OS 10.4 works with it. While I was having a myriad of network problems, I could connect to the Internet, retrieve my mail, etc. using my son's Mini, as well as an old Mac 7300. Both of these worked just fine connected to the network (router and DSL). Only my iMac G5 would not work.