Tried all possible combinations of the settings described above but neither worked.
The version I have is Antivirus 3.0.642.0.

Last solution: Uninstall and install the cd version which is older.

I hope in ESET, be more careful and do a thorough test before posting software with bugs.

I have the same NOD32 version (3.0.642.0) + VS2008 VWD and I found a temporary workaround (it's not safe):

1. DoubleClick on Nod32 icon on tray.
2. Go to Setup - Antivirus and antispyware protection
3. In the Web access protection click on "Configure..."
4. From the left Tree go to path : "Web access protection > HTTP > Web Browsers"
5. Clean the checkbox belonging to your browser (Internet Explorer, perhaps)
6. Stop ASP.NET Development server if running, restart browser

WARNING: This switches off protection of browser when surfing on web!!! Use it only temporarily during development.

 Thank You very much!!

EasternBoy:

i had the same problem and here is its fix,

as u have Eset nod32 antivirus v3.0.621 (same as me) , the problem is from this AV that dont allow connections to be made to Visual Studio ASP.NET Server .

now follow these steps to solve this issue:

1. DoubleClick on Nod32 icon on tray and Open it up.
2. if it is not in "Advanced Mode" , switch to Advanced Mode. ( you can do it by clicking on the bottom-left link "Display:Standard Mode" and then click on "Toggle Advanced Mode" )
3. then goto SETUP section. then on the Right Pane click on "Antivirus and Antispyware protection". the panel should be opened.
4. now in the "Web Access protection" click on "Configure..."
5. from the left Tree go to path : "Web access protection > HTTP > Web Browsers"
6. now you should see visual studio 8 "devenv.exe" in the list .
7. click on it twice till you see a cross sign in the box. ( Note on CROSS sign , not mark sign ! )
8. with this cross sign you tell the Nod32 that this program should not be scanned and filtered for web access.

due to this steps , my problem solved and now i can access my page from localhost:<portNumber> .