After installing the voodoo 2 driver for win 2000/XP (Glide +OpenGl) and rebooting , I recive the following message :
Genport I/O initialization failure .
This message  is generated by run32dll.exe.
Also the voodoo2 tab is not present ,but in the device  
manager the voodoo2 is listed and the system tells me  
that his status is OK . (?)
Also in games the driver is prezent  but it cannot be enabled.(Quake 3 for example)

posting full system specs would be a good start (hardware/software/drivers/windows).what voodoo2 driver are you trying to use?

I solved  the problem (90 %).It was a windows xp related problem.My voodoo 2 tab is prezent with all
information.
The problem was that the following item could not be
loaded at startup(running a dll as an application):
rundll32.exe 3dfxv2ps.dll,UpdateRegSettings
Now the voodoo2 is recognized but still a recive the
message error
Here are the main specifications:

Hardware:
CPU:AMD Duron 850 Mhz
RAM:128 SDRAM
Main Board:MSI MS-6378;
Video Board: onboard Trident Video Accelerator Blade  
                    3D  Promedia
3D Accelerator:3Dfx voodoo2 accelerator,revision A1  
                        12 Mb
Sound Card: onboard AC 97
Mouse,keyboard on PS/2

Software
OS system:Microsoft Windows XP Home edition ,
                 build 2600
Directx Media: Directx 8.1

Here are the voodoo2 driver main specifications:
driver version:1.01
(quoting from voodoo2.inf file):

;-----------------------------------------------------------------------
; INF file for Voodoo2 based 3D Accelerators running under Windows 2000
;
; (c) 1998-2000 - 3dfx Interactive, Inc.
;
; Installs Control Panel, OpenGL, and Glide drivers
;-----------------------------------------------------------------------

[version]
Class=MEDIA
signature="$CHICAGO$"
Provider=%3Dfx%
ClassGUID={4d36e96c-e325-11ce-bfc1-08002be10318}
DriverVer=3/2/2000,1.00.01

; Disk & Directory sections
;----------------------------------------
[DestinationDirs]
DefaultDestDir    = 11  ; system32
voodoo2.Miniport  = 12  ; drivers
voodoo2.Display   = 11  
Voodoo2Inf.Copy   = 17  
WinHelp.Copy      = 18  

;
; Driver information
;

; Manufacturers
;----------------------------------------
[Manufacturer]
%3Dfx% = 3Dfx.Mfg

; Driver sections
;----------------------------------------
[3Dfx.Mfg]
Voodoo2 3D Accelerator= voodoo2, PCI\VEN_121A&DEV_0002

; Install sections
;----------------------------------------
[voodoo2]
CopyFiles = voodoo2.Miniport, voodoo2.Display, Voodoo2Inf.Copy, WinHelp.Copy
AddReg    = voodoo2.AddReg, Control.Panel.Addreg
DriverVer = 3/2/2000

; Uninstall section
;----------------------------------------
[Voodoo2.Uninstall]
DelFiles   = voodoo2.Miniport, voodoo2.Display, Voodoo2Inf.Copy, WinHelp.Copy
DelReg     = voodoo2.AddReg, Control.Panel.Addreg
DelService = fxgpio, fxptl, Ntremap


[voodoo2.Miniport]
fxgpio.sys
fxptl.sys
ntremap.sys

[voodoo2.Display]
3dfxspl2.dll
3dfxspl3.dll
3dfxv2ps.dll
3dfxvgl.dll
csh.dll
fxoem2x.dll
glide2x.dll
glide3x.dll

[Voodoo2Inf.Copy]
voodoo2.inf

[WinHelp.Copy]
3dfxv2ps.hlp

[voodoo2.Services]
AddService = fxgpio,  0x00000002, fxgpio_Service_Inst
AddService = fxptl,   0x00000002, fxptl_Service_Inst
AddService = Ntremap, 0x00000002, Ntremap_Service_Inst

[fxgpio_Service_Inst]
DisplayName    = "Voodoo2 PCI Port I/O"
ServiceType    = 1                  ; SERVICE_KERNEL_DRIVER
StartType      = 2                  ; SERVICE_AUTO_START
ErrorControl   = 1                  ; SERVICE_ERROR_NORMAL
ServiceBinary  = %12%\fxgpio.sys
LoadOrderGroup = "Extended Base"

[fxptl_Service_Inst]
DisplayName    = "Voodoo2 Memory Mapper"
ServiceType    = 1                  ; SERVICE_KERNEL_DRIVER
StartType      = 2                  ; SERVICE_AUTO_START
ErrorControl   = 1                  ; SERVICE_ERROR_NORMAL
ServiceBinary  = %12%\fxptl.sys
LoadOrderGroup = "Extended Base"

[Ntremap_Service_Inst]
DisplayName    = "Voodoo2 Board Remapper"
ServiceType    = 1                  ; SERVICE_KERNEL_DRIVER
StartType      = 2                  ; SERVICE_AUTO_START
ErrorControl   = 1                  ; SERVICE_ERROR_NORMAL
ServiceBinary  = %12%\ntremap.sys
LoadOrderGroup = "Extended Base"

[voodoo2.AddReg]
HKLM,"Software\3Dfx Interactive"
HKLM,"Software\3Dfx Interactive\Ntremap","EnableNtremap",,"0x00000001"
HKLM,"Software\3Dfx Interactive\Voodoo2\Glide","SSTV2_RGAMMA",,"1.30"
HKLM,"Software\3Dfx Interactive\Voodoo2\Glide","SSTV2_GGAMMA",,"1.30"
HKLM,"Software\3Dfx Interactive\Voodoo2\Glide","SSTV2_BGAMMA",,"1.30"
HKLM,"Software\3Dfx Interactive\Voodoo2\Glide","SSTV2_REFRESH_512x384",,"60"
HKLM,"Software\3Dfx Interactive\Voodoo2\Glide","SSTV2_REFRESH_640x400",,"60"
HKLM,"Software\3Dfx Interactive\Voodoo2\Glide","SSTV2_REFRESH_640x480",,"60"
HKLM,"Software\3Dfx Interactive\Voodoo2\Glide","SSTV2_REFRESH_800x600",,"60"
HKLM,"Software\3Dfx Interactive\Voodoo2\Glide","SSTV2_REFRESH_1024x768",,"60"
HKLM,"SoftWare\Microsoft\Windows\CurrentVersion\Uninstall\3Dfx Interactive Voodoo2",,,
HKLM,"SoftWare\Microsoft\Windows\CurrentVersion\Uninstall\3Dfx Interactive Voodoo2","DisplayName",,"3Dfx Voodoo2 Display Driver and Control Panel"
HKLM,"SoftWare\Microsoft\Windows\CurrentVersion\Uninstall\3Dfx Interactive Voodoo2","UninstallString",,"%11%\rundll32.exe setupapi.dll,InstallHinfSection Voodoo2.Uninstall 132 %17%\Voodoo2.inf"

[Control.Panel.Addreg]
HKLM,"SoftWare\Microsoft\Windows\CurrentVersion\Run","Voodoo2",,"rundll32.exe 3dfxv2ps.dll,UpdateRegSettings"
HKCR,"CLSID\{00BD7141-4A41-11d1-89EA-0020AFC43773}",,,"3Dfx Voodoo2 Property Sheet"
HKCR,"CLSID\{00BD7141-4A41-11d1-89EA-0020AFC43773}\InProcServer32",,,"%11%\3dfxv2ps.dll"
HKCR,"CLSID\{00BD7141-4A41-11d1-89EA-0020AFC43773}\InProcServer32","ThreadingModel",,"Apartment"
HKLM,"Software\Microsoft\Windows\CurrentVersion\Controls Folder\Display\shellex\PropertySheetHandlers\Voodoo2",,,"{00BD7141-4A41-11d1-89EA-0020AFC43773}"
HKLM,"Software\3Dfx Interactive\Voodoo2\PropPage","LastHardware",,"33
HKLM,"Software\3Dfx Interactive\Voodoo2\PropPage","LastApi",,"Glide"
HKLM,"Software\3Dfx Interactive\Voodoo2\PropPage","HasBeenSwept",,"0x00000001"

[SourceDisksNames.x86]
1 = "3dfx Voodoo2 Install disk","voodoo2.cab",0

[SourceDisksFiles]
3dfxspl2.dll = 1
3dfxspl3.dll = 1
3dfxv2ps.dll = 1
3dfxv2ps.hlp = 1
3dfxvgl.dll  = 1
csh.dll      = 1
fxgpio.sys   = 1
fxoem2x.dll  = 1
fxptl.sys    = 1
glide2x.dll  = 1
glide3x.dll  = 1
ntremap.sys  = 1
voodoo2.inf  = 1

; User visible strings
;----------------------------------------
[Strings]
3Dfx   = "3Dfx Interactive, Inc."

(End quoting voodoo2 inf file)

I used  this driver for 6 months but never recived such an error message

uninstall your voodoo2 driver (add or remove programs in the control panel),and install the latest 3rparty voodoo2 winxp driver,like fastvoodoo2 4.0xp.

check here for recommended voodoo2 drivers and settings..

Thanks.Now it works fine.No message error