Vista - Windows Defender - how to access the public network again

I've run into a problem where I got a trojan horse detected by Windows Defender. On the same pc I have AVG AV installed as well, which might complicate matters further as well.

I tried to remove the trojans by following the on-screen prompts unsuccessfully...basically the prompts to remove the trojan keep coming up even though I hit Remove all (something like that).

OS: Windows Vista Business

Following some prompts windows sensibly suggested that access to public networks is going to be restricted (i.e. no access to Internet), and, I accepted for prudency's sake.

Any idea how to tell Windows that I want to access the public network (Internet) again, please?

P.S. No Administrator password, so I'm always being prompted for it for "elevated commands".

Any ideas would be appreciated.

Jon80,
You are running a server OS. Any other computers that are on this server could also be infected. This is a fake trojan from what your telling us.
Remove any current Antivirus, antimalware, and antispyware programs you may have installed. You will want to install MalwareBytes, Spybot S&D, and Avira to your computer. Install all 3 and make sure they update. From here, disconnect the router or modem form the computer/server so there is no internet access. do a restart.

Now run 1. MalwareBytes
2. Spybot S&D
3. Avira

Once you are done with these 3, install Ccleaner and run this. make sure that you go into settings and uncheck "only remove temporary files older then 24 hrs." Now, run the cleaner with all of the boxes checked. Now also run the registry cleaner.

Once you have done this, hopefully your server/computer will be up and running again like normal.

You will probably also want to do this for all the computers that have been connected to the server in the past 3 months or longer depending on how long you have had the problem.

Let us know,
Ben

Is Vista Business a server OS?

No. I saw that you are running that on your info. Look to the left of your post below mine. It says on the second line down that you are running vista server 2008 x64

I'm sorry that is out-of-date, because I sometimes manage a number of computers What I'm concerned about is how to get the pc connected again to the public network (i.e. Internet), because I didn't see any relevant options within Windows Defender.

Ok,
You can still follow my 1st post the same exact way. Make sure you do this on all the computers on the network.
This should solve your Windows Defender problem.
Let me know,
Ben