(Performance Issue)

I experience intermitent periods of freezing while playing on the Atlantis map. The Mine map doesn't have the same problem. The freeze last for up to 2 minutes and then resumes game play with out lag. Here is my Dxdiag.

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System Information
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Time of this report: 11/8/2008, 22:37:45
       Machine name: HOME
   Operating System: Windows XP Home Edition (5.1, Build 2600) Service Pack 2 (2600.xpsp_sp2_gdr.080814-1233)
           Language: English (Regional Setting: English)
System Manufacturer: Compaq Presario 061
       System Model: ED878AA-ABA SR1630NX NA540
               BIOS: Phoenix - AwardBIOS v6.00PG
          Processor: AMD Athlon(tm) 64 Processor 3500+,  MMX,  3DNow, ~2.2GHz
             Memory: 1022MB RAM
          Page File: 513MB used, 1580MB available
        Windows Dir: C:\WINDOWS
    DirectX Version: DirectX 9.0c (4.09.0000.0904)
DX Setup Parameters: Not found
     DxDiag Version: 5.03.2600.2180 32bit Unicode

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DxDiag Notes
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  DirectX Files Tab: No problems found.
      Display Tab 1: No problems found.
        Sound Tab 1: The file ALCXWDM.SYS is not digitally signed, which means that it has not been tested by Microsoft's Windows Hardware Quality Labs (WHQL).  You may be able to get a WHQL logo'd driver from the hardware manufacturer.
        Sound Tab 2: No problems found.
          Music Tab: No problems found.
          Input Tab: No problems found.
        Network Tab: No problems found.

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DirectX Debug Levels
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Direct3D:    0/4 (n/a)
DirectDraw:  0/4 (retail)
DirectInput: 0/5 (n/a)
DirectMusic: 0/5 (n/a)
DirectPlay:  0/9 (retail)
DirectSound: 0/5 (retail)
DirectShow:  0/6 (retail)

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Display Devices
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        Card name: NVIDIA GeForce 8600 GT
     Manufacturer: NVIDIA
        Chip type: GeForce 8600 GT
         DAC type: Integrated RAMDAC
       Device Key: Enum\PCI\VEN_10DE&DEV_0402&SUBSYS_C7563842&REV_A1
   Display Memory: 512.0 MB
     Current Mode: 1152 x 864 (32 bit) (60Hz)
          Monitor: hp L1702 flat panel monitor
  Monitor Max Res: 1280,1024
      Driver Name: nv4_disp.dll
   Driver Version: 6.14.0011.7519 (English)
      DDI Version: 9 (or higher)
Driver Attributes: Final Retail
 Driver Date/Size: 5/16/2008 13:01:00, 6108928 bytes
      WHQL Logo'd: Yes
  WHQL Date Stamp: n/a
              VDD: n/a
         Mini VDD: nv4_mini.sys