recently the portal stopped allowing all to login (saying wrong pwd), however after upgrading it with latest version it logs me in automatically (but logging out then trying to log in again says wrong password)

trying to send password via e-mail I get the following:

Server Error in '/portal' Application.

Invalid length for a Base-64 char array.

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.FormatException: Invalid length for a Base-64 char array.

Source Error:

Stack Trace:

				[FormatException: Invalid length for a Base-64 char array.]
   System.Convert.FromBase64String(String s) +0
   mojoPortal.Web.mojoMembershipProvider.UnencodePassword(String pass, MembershipPasswordFormat passwordFormat) +34
   mojoPortal.Web.mojoMembershipProvider.GetPassword(String userName, String passwordAnswer) +216
   System.Web.Security.MembershipUser.GetPassword(String passwordAnswer) +83
   System.Web.Security.MembershipUser.GetPassword(String answer, Boolean useAnswer, Boolean throwOnError) +48
   System.Web.UI.WebControls.PasswordRecovery.AttemptSendPasswordQuestionView() +321
   System.Web.UI.WebControls.PasswordRecovery.AttemptSendPassword() +69
   System.Web.UI.WebControls.PasswordRecovery.OnBubbleEvent(Object source, EventArgs e) +103
   System.Web.UI.Control.RaiseBubbleEvent(Object source, EventArgs args) +37
   System.Web.UI.WebControls.Button.OnCommand(CommandEventArgs e) +118
   System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +166
   System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +10
   System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +13
   System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +36
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1565

thanks for the tip, I guess the pwd in the mp_Users is corrupted or something (regarding the machine key, do you mean in the machine's web.config or in the site web.config [is there one?])

All the passwords are in plain text in the db (apart from the one for a new user I tried to register from the site's GUI [that has yet to be confirmed by the admin [which can't login]). So how can I login? Should I copy the encrypted pwd of the new user into mine or does the encrypted pwd contain info about the user name or other data too that doesn't allow me to copy/paste it to other user rows?

Also do you have a hint on why this happened? Was it result of some site upgrade? (last upgrade that may have caused the issue was from mojoportal-2-3-3-2-mssql-deploymentfiles to mojoportal-2-3-4-3-mssql-deploymentfiles - and now I uploaded mojoportal-2-3-4-5-mssql-net35-deploymentfiles [btw what's difference with the ver for .net 4?])