Proplem with SQL 2005

Hi
I have a problem with SQL 2005.

I had installed in my PC SQL Express and it with working fine with my Windows XP SP2 and VWD untill one day with I tried to lunch ASP.NET Configuration and clicked on Security , and then it showed me message " Unable to connect to SQL Server database." , i don't know what happend!!!
Here's link to screen shot about the message...
http://www.unlimitednetwork.net/data/screen_shot_1.JPG

After 2 days i Installed SQL 2005 Standerd , I said my be there's something wrong with Express version. After installed SQL Standerd still the same problem.

When i lunch Microsoft SQL Server Mangement Studio it's working fine.

And when I go to my Computer and Right Click and chose Mange it showed me that SQL 2005 working fine beside SQL 2000, but still show me message that it's not working, i don't know why!!!
Here's link to screen shot about the message...
http://www.unlimitednetwork.net/data/screen_shot_2.JPG

It's big and serious problem for me, i can't do anything, I have web site i have to finsh it soon.!!

So do you know where it can be the problem and how to solve it?!!...

another screen shot about my Computer Management to show my SQL how it's connect normaly..
http://www.unlimitednetwork.net/data/screen_shot_3.JPG

PS..
My Computer Name is AHMED
My SQL Server 2005 Name is NADA2005
My SQL Server 2000 Name is NADA or local ( it's working with both )

Thanks alot

Ahmed

Make sure that the instancename is specified in the connectionstring for the ASP application. if SQL Server Browser Server is no longer running start it (to let is redirect the application to the appropiate port, as I assume, Port 1433 is already occupied by the 2k instance) or specify the port number after the instancename with the syntax as:

ServerName\InstanceName,portnumber

HTH, Jens Suessmeyer.

http://www.sqlserver2005.de