Partial Reconfiguration:Par fails during Assemble

Hello,

I get the following error when I run Par during the assemble stage of the Partial Reconfiguration Flow.

The command I used was

par -w blinky_map.ncd blinky.ncd blinky.pcf

The error is

Starting Guide File Processing.

Loading device database for application Par from file
"../../Pims/configcontroller/configcontroller.ncd".
   "blinky" is an NCD, version 2.38, device xc2v4000, package ff1152, speed -5
The STEPPING level for this design is 0.
FATAL_ERROR:Guide:basgitaskphyspr.c:255:1.28.20.1.14.1:137 - Guide encountered a
   Logic0 or Logic1 signal GLOBAL_LOGIC1_57 that does not have a driver or load
   within the module boundary. This problem may be caused by having a constant
   driving the input from outside the module boundary or because a driver or
   load comp did not meet the par-guiding criteria. The design will not be
   completely placed and routed by Par-Guide Process will terminate. To
   resolve this error, please consult the Answers Database and other online
   resources at http://support.xilinx.com. If you need further assistance,
   please open a Webcase by clicking on the "WebCase" link at
   http://support.xilinx.com

When I bring up the active module implementation in the FPGA editor, this GND signal is inside the bounderies of the module. It has been inserted by the Xilinx tools and is not something I explicitely used in my design. I will really appreciate if someone can give me a pointer on how to resolve this. I have seached the Xilinx Answer database but did not find any useful tips.