Turns out it's not as intermittent as I thought.  It always changes to IDs on all other rows that do not have the same Subcategory.

What I have is a part list...The user picks a category from a webcombo which invokes a selectWhere on the Subcategory webcombo and only shows the subcategories that goes with the category.  The same thing for the parts webcombo, it chooses only parts in that subcategory.  I've narrowed down the problem to this selectWhere...if I don't do this selectWhere, everything works great.  Is there another way to do this?

Right now I have it in afterExitEditMode, but it does the same thing if I put the code in beforeEnterEditMode and change the column.Key values that will invoke the selectWhere.

function MainGrid_AfterExitEditModeHandler(gridName, cellId){
    var cell = igtbl_getCellById(cellId);
    var row = cell.Row;
    var column = cell.Column;
    if (column.Key == "PartServiceID") {
        igtbl_needPostBack(gridName);
    }
    else if (column.Key == "Quantity") {
        igtbl_needPostBack(gridName);
    }
    else if (column.Key == "CategoryID") {
        var cat = row.getCell(2).getValue(true);
        if (cat) {
            var subcatCombo = igcmbo_getComboById('ctl00xcntContentxSubcategoryController');
            subcatCombo.selectWhere("CategoryID='" + cat + "'");
        }
    } else if (column.Key == "SubCategoryID") {
        var subcat = row.getCell(3).getValue(true);
        if (subcat) {
            var partCombo = igcmbo_getComboById('ctl00xcntContentxPartController');
            partCombo.selectWhere("SubCategoryID='" + subcat + "'");
        }
    }   
   
}