Error (0xe0050401) from VPBrick driver: invalid hBrick

Hello,
can somebody help me ? I've just installed RIS 2.0 and when I try to set
"Lego Tower USB" parameters, I see in shooter.txt :
"RIS 2.0 Diagnostic Trouble Shooter
Date: 06/02/2006
Time: 20:34:46
Computer: DOMICILE-2OM1MW
User name: Papa
Processor Type: 586 (2)
Windows 2000 DETERMNIE IF PROFESSIONAL OR SERVER in DIAGNOSE.CPP version
5.1 Service Pack 2 (Build 2600)
VPBrick DLL version: 1,0,0,2
Xlate DLL version: 1,0,0,1
Script DLL version: 1,0,2,9
Brick DLL version: 1,0,0,3
LASM version: 1,0,0,0
RCX2BLT version: 1,0,0,134
Ghost PbkComm32 DLL version: 0,9,0,90
Ghost PbkUsbPort DLL version: 0,3,45,145
Diagnosing Error failed:
Error (0xe0050401) from VPBrick driver: invalid hBrick
Get Tower Type:
Get port name failed:
Error (0xe0050401) from VPBrick driver: invalid hBrick
Trouble Shooter closed
Time: 20:35:02"
Thank you to all for your help.