I killed the Member list installing DNN 5.1.

Here's the error log.

Method: DNNMasters.UserDirectoryManager.UDM_Grid.AddColumnsToGrid
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 DNNMasters.UserDirectoryManager.UDM_Grid.AddColumnsToGrid(String colName, GridLevel level, Int32 width) at DNNMasters.UserDirectoryManager.UDM_Grid.buildDataSource(String search1name, String search1value, String search1operator, Int32 search1profile, String search2name, String search2value, String search2operator, Int32 search2profile, String search3name, String search3value, String search3operator, Int32 search3profile, String mainOperator, Int32 pageSize, String sortName, String sortDir, Int32 pageIndex) at DNNMasters.UserDirectoryManager.UDM_Grid.buildSearchRequest(String sortName, String sortDir, Boolean allData, Boolean noData) at DNNMasters.UserDirectoryManager.UDM_Grid.Page_Load(Object sender, EventArgs e) at System.Web.UI.Control.OnLoad(EventArgs e) at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) --- End of inner exception stack trace ---

I installed the module on 5.1.0 and nothing untoward happened.
Everything seems to be working as expected.

Something happened with upgrade that killed it. Not really sure what, but it does work with a clean install, so I guess I'll be importing data and such to the new installation.

I migrated all my data to a new install of 5.1. The grid doesn't crash, but the search operators show up as Operator1-14. I installed the 3.51 update, and now the grid renders only at the height set making any other records inaccessible below what the height setting will display requardless of what the page size is set to. There are no scroll bars to let you get to the other rows. In my case, I have page set to 25, but at 500 height, only 8 rows display, and the rows in the page set below them are inaccessible. I do however like that the search link is no longer visible when the search options are not being used.

Weird, I upgraded my 5.1.0 to UDM 3.5.1 and see everything normal under IE8 and FF3.5.
Data rows shouldn't overflow the container - adjust height & rows settings

I imported more users to have the grid nicely populated.
Set the grid height to 300 and rows to 25 - search nicely extended grid down so that all rows fit in.

Also, in 3.51 the Directory module is giving me an error. I guess I will try uninstalling all modules and reinstall to see if it will correct the problems I am seeing.

I confirm the bug in Directory View on 3.5.1.
Will fix asap.

Fixed and tested. New version uploaded on www.dnnmasters.com