Scenario:
- I have installed Wordpress MU in localhost (local computer).
- I am using Windows XP Operating System.
- I am using WAMP Server.
Problem:

Problem:
I had a new installation of magento. But I was unable to login as an administrator. I went to the admin login page, entered correct username and password but was redirected to the same login page. I could not enter the dashboard page. Error message is displayed when I enter wrong username or password. But nothing is displayed and I am redirected to the same login page when I insert correct username and password.
Solution:

Error:
A potentially dangerous Request.Form value was detected from the client
Scenario:
When you put html tags in your form fields (textbox,textarea) like

Error description:
Cannot insert the value NULL into column ‘SourceId’, table ‘Advisory.dbo.AdvDocSource’; column does not allow nulls. INSERT fails.
The statement has been terminated. The ‘CompanyAdd’ procedure attempted to return a status of NULL, which is not allowed. A status of 0 will be returned instead.
——————————-

This error occurs because the ‘SourceId’ column in my table is primary key and it is set to not null. i.e. it doesn’t allow null entries. And I have not made it auto increment.

This error might occur if you have selected your selection list (dropdownlist) multiple times. You can add multiple=”true” e.g.
in your selection list so as to enable multiple item select.

If you don’t want your selection list to be multiple select enabled then you have to check whether you have selected the selection list multiple times either in your design (aspx file) or in code (aspx.cs file).