I'm developing web application in as.net and the most bizarre situation ocurred. in this application i am using only one aspx page ,When I select any item from dropdownliast then pageload is called again & again , and the dropdownliast_selectedomdexchanged method is called right after that. then page is loaded again , after selecting anything from downlist this task happens twice , But, unexpectedly, the Page_Load method of the Login page is also called! And strangest of all: the WebForm page is displayed.
how to resolve this problem??

plz use AJAX control for that ... in that the page can't be reloaded..

which type of ajax control to be used ??
please tell me.

if u are using asp.net 2.0 ,u can download ajaxcontrol tool kit and ajax extensions 1.0 from www.msdn.com website.
and add dlls to ur website.
select updatepanel from the ajax extensions and it to the control u dont want to make the page reload.