               */
              startInterval: function() {
 -                if (!this._interval) {
-+                if (this._interval != null) {
++                if (this._interval == null) {
                      var self = this;
                      var callback = function() { self._tryPreloadAttach(); };
                      this._interval = setInterval(callback, this.POLL_INTERVAL);

                     this.startInterval();
                 } else {
-                    if (this._interval) {
+                    if (this._interval == null) {
                         clearInterval(this._interval);
                         this._interval = null;
                     }

                 if (onAvailStack.length === 0) {
                     retryCount = 0;
-                    if (this._interval) {
+                    if (this._interval != null) {
                         clearInterval(this._interval);
                         this._interval = null;
                     } 
