Cant launch ModelSim from Xilin ISE 12.1

Hi, 
I am developing a design using xilinx ISE 12.1. I have selected ModelSim
6.5 SE for simulations. When i run behavi{*filter*}simulation following error
comes:


 ----------------------------------------------------------------------------
 * udo file already exist (pie_tb.udo). It will not be re-generated.
 * creating main do file (pie_tb.fdo) for Behavi{*filter*}Simulation...
    > executing 'D:/modeltech_6.5/win32/vsim.exe -version' to get the
mti_se version...
    > Modelsim version is 6.5
 * determining pre-compiled simulation library path information...
   > using mapping file set by MODELSIM env (D:\modeltech_6.5)...

ERROR: Unable to read the "D:\modeltech_6.5" file.
Reason: couldn't open "D:\modeltech_6.5": permission denied

INFO: Simulation process aborted!
----------------------------------------------------------------------------

any one can please help me and tell me why this problem arise. I am using
administrator account and i also give full rights to modelsim folder. Also
my integrated tools option is set correctly point towards modelsim exe
file.
please guide me how to remove this error.
Thanks in advance	   
					
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Not sure if it helps but Mentor's Supportnet newsletter had this today:

Problems running ModelSim from Xilinx ISE

Symptoms

You have more than one simulator loaded, or have replaced an existing one with 
another.
The Xilinx compiled libraries are not valid for the simulation. The default 
information in the modelsim.ini file are not correct.

Causes

The Xilinx project accesses ModelSim from 3 different places, and if they don't 
all point to the same install problems can arise.

Solution

Check that the following all point to the same install:

1) Environment path (check that only one path points to the modelsim 
executables), remove all others. You should have one valid path (Xilinx uses it 
to create the default modelsim.ini file using "vmap -c".
2) Xilinx top Menu: Edit --> Preferences -- ISE General -- Integrated Tools --  
Model Tech Simulator: Example: <Drive>:\<install_dir>\win32pe\modelsim.exe
3) Window "View": M Simuilation; highlight the device in the Hierarchy window. 
Expand Design Utilities and Right Mouse Button 'Compile HDL Simulation 
Libraries' and select 'Process Properties': fill in the GUI as needed.


Hans
www.ht-lab.com

"muhammad_umer" < XXXX@XXXXX.COM > wrote in