diff --git a/uriloader/exthandler/nsHandlerService.js b/uriloader/exthandler/nsHandlerService.js
index 6709ba3782c1..5e8ca95d6423 100755
--- a/uriloader/exthandler/nsHandlerService.js
+++ b/uriloader/exthandler/nsHandlerService.js
@@ -362,8 +362,29 @@ HandlerService.prototype = {
     this._removeAssertions(preferredHandlerID);
 
     var infoID = this._getInfoID(this._getClass(aHandlerInfo), aHandlerInfo.type);
+
+    // Get a list of possible handlers.  After we have removed the info record,
+    // we'll check if any other info records reference these handlers, and we'll
+    // remove the handler records that aren't referenced by other info records.
+    var possibleHandlerIDs = [];
+    var possibleHandlerTargets = this._getTargets(infoID, NC_POSSIBLE_APP);
+    while (possibleHandlerTargets.hasMoreElements()) {
+      let possibleHandlerTarget = possibleHandlerTargets.getNext();
+      // Note: possibleHandlerTarget should always be an nsIRDFResource.
+      // The conditional is just here in case of a corrupt RDF datasource.
+      if (possibleHandlerTarget instanceof Ci.nsIRDFResource)
+        possibleHandlerIDs.push(possibleHandlerTarget.ValueUTF8);
+    }
+
+    // Remove the info record.
     this._removeAssertions(infoID);
 
+    // Now that we've removed the info record, remove any possible handlers
+    // that aren't referenced by other info records.
+    for each (let possibleHandlerID in possibleHandlerIDs)
+      if (!this._existsResourceTarget(NC_POSSIBLE_APP, possibleHandlerID))
+        this._removeAssertions(possibleHandlerID);
+
     var typeID = this._getTypeID(this._getClass(aHandlerInfo), aHandlerInfo.type);
     this._removeAssertions(typeID);
 
@@ -1250,9 +1271,12 @@ HandlerService.prototype = {
     var properties = this._ds.ArcLabelsOut(source);
  
     while (properties.hasMoreElements()) {
-      var property = properties.getNext();
-      var target = this._ds.GetTarget(source, property, true);
-      this._ds.Unassert(source, property, target);
+      let property = properties.getNext();
+      let targets = this._ds.GetTargets(source, property, true);
+      while (targets.hasMoreElements()) {
+        let target = targets.getNext();
+        this._ds.Unassert(source, property, target);
+      }
     }
   }