Pls suggest me how to solve the problem...<< :)

[NannMaw]

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Server Error in '/WebSite1' Application.
--------------------------------------------------------------------------------

Invalid postback or callback argument. Event validation is enabled using <pages enableEventValidation="true"/> in configuration or <%@ Page EnableEventValidation="true" %> in a page. For security purposes, this feature verifies that arguments to postback or callback events originate from the server control that originally rendered them. If the data is valid and expected, use the ClientScriptManager.RegisterForEventValidation method in order to register the postback or callback data for validation.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.ArgumentException: Invalid postback or callback argument. Event validation is enabled using <pages enableEventValidation="true"/> in configuration or <%@ Page EnableEventValidation="true" %> in a page. For security purposes, this feature verifies that arguments to postback or callback events originate from the server control that originally rendered them. If the data is valid and expected, use the ClientScriptManager.RegisterForEventValidation method in order to register the postback or callback data for validation.

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:


[ArgumentException: Invalid postback or callback argument. Event validation is enabled using <pages enableEventValidation="true"/> in configuration or <%@ Page EnableEventValidation="true" %> in a page. For security purposes, this feature verifies that arguments to postback or callback events originate from the server control that originally rendered them. If the data is valid and expected, use the ClientScriptManager.RegisterForEventValidation method in order to register the postback or callback data for validation.]
System.Web.UI.ClientScriptManager.ValidateEvent(St ring uniqueId, String argument) +358
System.Web.UI.Control.ValidateEvent(String uniqueID, String eventArgument) +108
System.Web.UI.WebControls.DropDownList.LoadPostDat a(String postDataKey, NameValueCollection postCollection) +52
System.Web.UI.WebControls.DropDownList.System.Web. UI.IPostBackDataHandler.LoadPostData(String postDataKey, NameValueCollection postCollection) +11
System.Web.UI.Page.ProcessPostData(NameValueCollec tion postData, Boolean fBeforeLoad) +381
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +2965


<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< <

Hi, I got this error when I run my page on IE browser. I got no errors with FireFox .If there is anything to solve this problem, let me know.
Thanks.

[Plater]

You could turn off event validation like it says?
All it's doing is trying to make sure there are no postbacks that don't come specifically from aspnet controls.

[NannMaw]

You could turn off event validation like it says?
All it's doing is trying to make sure there are no postbacks that don't come specifically from aspnet controls.

Hi,Plater, I add "EnableEventValidation="true" in Page directive. Then the error changes to :
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
Server Error in '/WebSite1' Application.
--------------------------------------------------------------------------------

Validation of viewstate MAC failed. If this application is hosted by a Web Farm or cluster, ensure that <machineKey> configuration specifies the same validationKey and validation algorithm. AutoGenerate cannot be used in a cluster.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.Web.HttpException: Validation of viewstate MAC failed. If this application is hosted by a Web Farm or cluster, ensure that <machineKey> configuration specifies the same validationKey and validation algorithm. AutoGenerate cannot be used in a cluster.

<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< <<<<<<<<
I wonder why its is ok when I run on FireFox.I got the errors when running IE browser.

Thanks 4 ur help.