I am suddenly having a problem with an error stopping at this code in MojoPortal.Web.MojoMembershipProvider at the following code:

byte[] bRet = DecryptPassword(bIn);

in this method:

UnencodePassword(string pass, MembershipPasswordFormat passwordFormat)
        {
            switch (passwordFormat)
            {
                case MembershipPasswordFormat.Clear:
                    return pass;
                case MembershipPasswordFormat.Hashed:
                    throw new ProviderException("Can't decrypt hashed password");
                default:
                    byte[] bIn = Convert.FromBase64String(pass);
                    byte[] bRet = DecryptPassword(bIn);
                   
                    if (bRet == null)
                        return null;

                    return Encoding.Unicode.GetString(bRet);
            }
        }

The error:

ERROR mojoPortal.Web.Global - 127.0.0.1-en-US - /Admin/SiteSettings.aspx
System.Web.HttpException (0x80004005): Unable to validate data.
   at System.Web.Configuration.MachineKeySection.EncryptOrDecryptData(Boolean fEncrypt, Byte[] buf, Byte[] modifier, Int32 start, Int32 length, Boolean useValidationSymAlgo, Boolean useLegacyMode, IVType ivType, Boolean signData)
   at System.Web.Security.MembershipAdapter.EncryptOrDecryptData(Boolean encrypt, Byte[] buffer, Boolean useLegacyMode)
   at System.Web.Security.MembershipProvider.DecryptPassword(Byte[] encodedPassword)
   at mojoPortal.Web.mojoMembershipProvider.UnencodePassword(String pass, MembershipPasswordFormat passwordFormat) in                      ~\mojoportal\Web\Components\mojoMembershipProvider.cs:line 1429
   at mojoPortal.Web.SiteUtils.Decrypt(String encrypted) in ~\mojoportal\Web\Components\SiteUtils.cs:line 2148
   at mojoPortal.Web.AdminUI.SiteSettingsPage.PopulateMailSettings() in ~\mojoportal\Web\Admin\SiteSettings.aspx.cs:line 968
   at mojoPortal.Web.AdminUI.SiteSettingsPage.PopulateControls() in ~\mojoportal\Web\Admin\SiteSettings.aspx.cs:line 541
   at mojoPortal.Web.AdminUI.SiteSettingsPage.Page_Load(Object sender, EventArgs e) in ~\mojoportal\Web\Admin\SiteSettings.aspx.cs:line 96
   at System.Web.UI.Control.OnLoad(EventArgs e)
   at mojoPortal.Web.mojoBasePage.OnLoad(EventArgs e) in ~\mojoportal\Web\Components\mojoBasePage.cs:line 695
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)

I found 7 items in this forum with the same problem ut none of the solutions worked for me. I even recreated a new project from Mercurial in case there was a problem I couldn't find. Got rid of all cookies and history. The only thing I haven't done is to download a new database and start all over. Hope I don't have to take that route. Please help. Everything was going smooth for a long time and now this.