What driver version are you using?
 
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Supermicro P6DBE Rev 3.0 Motherboard
Dual Intel Pentium III 850
512 MEGS of ECC RAM
Sound Blaster Live!
Adaptec 29160 SCSI Card
GeForce 2 GTS 64MB
IBM DMVS18N Ultra 160 Hard Drive
Western Digital 20.5GB Hard Drive
Razer Boom Slang 2000 (USB)
Roland Sound Canvis SC-55
3COM 3CR990-TX-97 with 3XP Processor 10/100 PCI Network Interface Card
Plextor Plexwriter 12/4/32
Pioneer 10X DVD-ROM
Sony GDM-F500R Monitor

Try enabling SMP in Quake 3:
 
r_smp 1

most of us have found you have to enable the /realtime flag with r_smp 1 to get SMP to work. Unfortunately, it drops your fps by 20% or so instead of increasing it. I don't believe the detonator2 drivers are SMP equipped. So, here's the setting you need in your shortcut, but honestly, I'd skip it for now.
 
C:\WINNT\system32\cmd.exe /c start /realtime D:\Games\Quake_III_Arena\quake3.exe +set r_smp 1
 
Season directory information to taste...
 
:}
 
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W2K Pro(Purchased Retail, ACPI/SMP)
Supermicro SBDBS r1.02, Bios 3.0 (dead on-board SCSI chip)
2xPIII @450mhz (not o/c)
256mb PC100 Ram in 2 sticks
3xIDE HDs (50gb total, all NTFS) and 1 Pioneer IDE DVD-ROM (all UDMA)
Geforce 256 DDR (32mb), CL AnnPro (DET v5.32)
SBLive! Platinum with digital breakout card (LW3.0)
3COm 3C515-TX ISA Ethernet 10/100 (W2k CD)
SIIG AP-40 UWide SCSI PCI (W2K CD)
Nikon LS-2000 SCSI film scanner (drivers now released)
Sony SDT-9000 SCSI 4mm DAT (W2K CD)
SAF 4012 SCSI CD-Write (W2K CD)
Iomega Zip 100 SCSI Drive (no drivers)
MS Natural Keyboard Pro USB (updated MS drivers)
MS Intellimouse Optical USB (updated MS drivers)
HP Laserjet 6L via USB printing (W2K CD)
Epson Stylus Photo 700 via parallel
Rainbow Sentinel Parallel Dongle for LightWave6

Right now I'm running the 5.32 driver version I will try going back to the 5.22's... I already have tried the command r_smp 1 and when I start q3 it locks up just prior to getting the id logo.... i'll swap out drivers and see if that has any change....

If you dont give quake3 realtime, it will freeze.

I must be in the minority when it comes to Quake III and SMP. I am running in SMP on my system with no problems what so ever. I am using the Detonator 5.32 drivers for my video card. Everything works great. Even and 1600X1200 32-bit Color!!
 
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System Specs:
Asus P2B-D
Dual PIII 700MHz
512MB PC100 RAM
Elsa GeForce2 GTS 64MB Video Card
Promise Ultra66 Controller
WD 15.3 GB HDD
WD 20.5GB HDD
Asus 50x CD-ROM
Sony 4x4x24 CD-RW
SB Live! Platinum
SuperMicro SC-750A Case w/ 400 Watt PS