Make my application start with Administration right when Windows Log on

For better view check your SQL Logs, might sql killing all your connection during startup.

Did you tried rebooting the system and also restrarting the SQL Sevices, just a workaround might helps :).

For error 1, refer forum

For error 2, set connection pooling=true in the connection string.

Do you know what is causing those errors? It is likely the solution is easy if you know the cause. Without knowing the cause, it is not possible to know if Access will solve it. It is possible to know if Access will have other problems.

Do you think that an Access database will avoid those errors.?

A database application should not need Administrator privileges. If the problem is that the SQL Server is not executing, Administrator privileges won't help. Instead of speculating and guessing, just look to see if  the SQL Server is executing; that is easy to do.If it is not executing, then start it. If it starts and then your application works, then you can figure out later how to fix it so it starts automatically. If the application still does not work, then try using the database using something else, such as Visual Studio. If you can't use the database with something else such as VS then you know it is not your application.


It helps to diagnose problems methodically in the preceding manner.

Try this
http://msdn.microsoft.com/en-us/library/bb756929.aspx
http://www.developerfusion.com/code/7987/making-a-net-app-run-on-vista-with-administrator-priviledges/

The following two errors appears during the program startup:

I think the SQL service does not start at windows logon maybe this cause this error... thnx

It depends upon only your user account, how it configured. Add your user account into Adminstrator group with full rights.

The error message says "or the server is not responding". Probably it is not responding because it is not started. Occasionally SQL Server in my system is not running; it usually starts automatically and I don't know why it stops when it does. If SQL Server is stopped, then just start it.
 
Note that for the question about use of Administrator access, security experts will strongly advise not to do that; you should not use Administrator access unless there is clearly a need for it. You should determine what the problem is that requires Administrator access. A likely explanation is that the database is located someplace it should not be. You should use this as an opportunity for learning how to debug problems.

Which user account did you set on the task properties?  Does that account have Administrator rights?

The schedule helped me but the following error is appearing :

Try using a scheduled task to run the app on startup.  With a scheduled task you can assign any user account to run the task as.