--- DotNetNuke 4.4.1; SQL Server 2005 Express ---

Logged in as HOST, I make modifications to Users > Manage Profile Properties:

Deleting a few properties
Adding a few new properties

After saving modifications, when Registered Users attempt to make a change to their profile (Manage Profile > Update), the Profile changes are saved, but the following error displays:

A critical error has occurred.
Object reference not set to an instance of an object.

Here are details from Admin > Log Viewer:

Log Type: Page Load Exception

AssemblyVersion: 04.04.01
PortalID: 2
UserID: 11
ActiveTabID: 70
ActiveTabName: Home
RawURL: /Home/tabid/70/ctl/Profile/UserID/11/Default.aspx
AbsoluteURL: /Default.aspx
UserAgent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; (R1 1.5); .NET CLR 1.1.4322)
DefaultDataProvider: DotNetNuke.Data.SqlDataProvider, DotNetNuke.SqlDataProvider
ExceptionGUID: 7868a991-0fe1-4813-a1d5-b0c8bdd36957
InnerException: Object reference not set to an instance of an object.
FileName:
FileLineNumber: 0
FileColumnNumber: 0
Method: DotNetNuke.Modules.Admin.Users.ManageUsers.ProfileUpdateCompleted
StackTrace:
Message: DotNetNuke.Services.Exceptions.PageLoadException: Object reference not set to an instance of an object. ---> System.NullReferenceException: Object reference not set to an instance of an object.at DotNetNuke.Modules.Admin.Users.ManageUsers.ProfileUpdateCompleted(Object sender, EventArgs e)at DotNetNuke.Modules.Admin.Users.Profile.OnProfileUpdateCompleted(EventArgs e)at DotNetNuke.Modules.Admin.Users.Profile.cmdUpdate_Click(Object sender, EventArgs e)at DotNetNuke.UI.WebControls.CommandButton.RaiseClick(Object sender, EventArgs e)at System.Web.UI.WebControls.LinkButton.OnClick(EventArgs e)at System.Web.UI.WebControls.LinkButton.RaisePostBackEvent(String eventArgument)at System.Web.UI.WebControls.LinkButton.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument)at System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument)at System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData)at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)--- End of inner exception stack trace ---
Source:

I add back all the Profile properties I had deleted; still the error exists.
The error does not occur when Admin or Host edit their profile.

Any suggestions for resolution would be very welcome.

I took a look into the ProfilePropertyDefintion table, but it was full of records. This DNN installation has several portals, and the table had lots of Deleted and Added records. It was not easy to sort out which properties I deleted and added to which portal.

I decided to rollback to a previous backup, full database, which worked to rid the error.

Best advice I can give is: be sure you have a full backup before you modify Manage Profile Properties. Even though the option is there, DO NOT delete existing profile properties. Disable Visibility for existing/default properties and "Add New Profile Property" with caution.