Good day all,
I've been having this problem for quite sometime now. Whenever i start my pc, i need to reinstall my modem coz i got this error 797 whenever i tried to connect. This is my hijackthis log. Hopefully this could solve the problem. Thx in advance.

Logfile of HijackThis v1.98.2
Scan saved at 10:48:15 AM, on 11/10/2004
Platform: Windows XP (WinNT 5.01.2600)
MSIE: Internet Explorer v6.00 (6.00.2600.0000)

Running processes:
C:\WINDOWS\System32\smss.exe
C:\WINDOWS\system32\winlogon.exe
C:\WINDOWS\system32\services.exe
C:\WINDOWS\system32\lsass.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\System32\svchost.exe
C:\WINDOWS\system32\spoolsv.exe
C:\Program Files\Common Files\Symantec Shared\ccEvtMgr.exe
C:\Program Files\Norton AntiVirus\navapsvc.exe
C:\WINDOWS\System32\nvsvc32.exe
C:\WINDOWS\System32\svchost.exe
C:\WINDOWS\system32\ZONELABS\vsmon.exe
C:\WINDOWS\Explorer.EXE
C:\WINDOWS\SOUNDMAN.EXE
C:\Program Files\Common Files\Symantec Shared\ccApp.exe
C:\WINDOWS\System32\regscan32.exe
C:\Program Files\HP\HP Software Update\HPWuSchd.exe
C:\Program Files\HP\hpcoretech\hpcmpmgr.exe
C:\WINDOWS\System32\DSLAGENT.EXE
C:\PROGRA~1\ZONELA~1\ZONEAL~1\zlclient.exe
C:\WINDOWS\System32\rundll32.exe
C:\Program Files\Spybot - Search & Destroy\TeaTimer.exe
C:\Program Files\HP\Digital Imaging\bin\hpqtra08.exe
C:\WINDOWS\System32\NotifyPhoneBook.exe
C:\Program Files\HP\hpcoretech\comp\hptskmgr.exe
C:\WINDOWS\System32\wuauclt.exe
C:\PROGRA~1\Netscape\Netscape\Netscp.exe
C:\PROGRA~1\WINZIP\winzip32.exe
C:\Program Files\Messenger\msmsgs.exe
C:\Program Files\Hijackthis\HijackThis.exe

R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = http://www.hardwarezone.com.sg/
R1 - HKCU\Software\Microsoft\Internet Connection Wizard,ShellNext = http://servicestage.symantec.com/tec...build=STANDARD
N3 - Netscape 7: user_pref("browser.startup.homepage", "www.yahoo.com.sg"); (C:\Documents and Settings\mamapapa\Application Data\Mozilla\Profiles\default\qq2mn0z6.slt\prefs.js)
N3 - Netscape 7: user_pref("browser.search.defaultengine", "engine://C%3A%5CPROGRA%7E1%5CNetscape%5CNetscape%5Csearchplugins%5CSBWeb_01.src"); (C:\Documents and Settings\mamapapa\Application Data\Mozilla\Profiles\default\qq2mn0z6.slt\prefs.js)
O2 - BHO: AcroIEHlprObj Class - {06849E9F-C8D7-4D59-B87D-784B7D6BE0B3} - C:\Program Files\Adobe\Acrobat 5.0\Reader\ActiveX\AcroIEHelper.ocx
O4 - HKLM\..\Run: [SoundMan] SOUNDMAN.EXE
O4 - HKLM\..\Run: [NvCplDaemon] RUNDLL32.EXE C:\WINDOWS\System32\NvCpl.dll,NvStartup
O4 - HKLM\..\Run: [ccApp] "C:\Program Files\Common Files\Symantec Shared\ccApp.exe"
O4 - HKLM\..\Run: [ccRegVfy] "C:\Program Files\Common Files\Symantec Shared\ccRegVfy.exe"
O4 - HKLM\..\Run: [Windows Messenger] msmsgs.exe
O4 - HKLM\..\Run: [Windows Registry Scan] regscan32.exe
O4 - HKLM\..\Run: [HP Software Update] "C:\Program Files\HP\HP Software Update\HPWuSchd.exe"
O4 - HKLM\..\Run: [HP Component Manager] "C:\Program Files\HP\hpcoretech\hpcmpmgr.exe"
O4 - HKLM\..\Run: [DSLAGENTEXE] DSLAGENT.EXE USB
O4 - HKLM\..\Run: [Zone Labs Client] C:\PROGRA~1\ZONELA~1\ZONEAL~1\zlclient.exe
O4 - HKLM\..\Run: [SSC_UserPrompt] C:\Program Files\Common Files\Symantec Shared\Security Center\UsrPrmpt.exe
O4 - HKLM\..\Run: [AME_CSA] rundll32 amecsa.cpl,RUN_DLL
O4 - HKLM\..\RunServices: [Windows Messenger] msmsgs.exe
O4 - HKLM\..\RunServices: [Windows Registry Scan] regscan32.exe
O4 - HKCU\..\Run: [Windows Messenger] msmsgs.exe
O4 - HKCU\..\Run: [SpybotSD TeaTimer] C:\Program Files\Spybot - Search & Destroy\TeaTimer.exe
O4 - HKCU\..\Run: [Mozilla Quick Launch] "C:\Program Files\Netscape\Netscape\Netscp.exe" -turbo
O4 - HKCU\..\Run: [MSMSGS] "C:\Program Files\Messenger\msmsgs.exe" /background
O4 - Global Startup: HP Digital Imaging Monitor.lnk = C:\Program Files\HP\Digital Imaging\bin\hpqtra08.exe
O8 - Extra context menu item: Download All by FlashGet - C:\PROGRA~1\FLASHGET\jc_all.htm
O8 - Extra context menu item: Download using FlashGet - C:\PROGRA~1\FLASHGET\jc_link.htm
O8 - Extra context menu item: E&xport to Microsoft Excel - res://C:\PROGRA~1\MICROS~2\OFFICE11\EXCEL.EXE/3000
O9 - Extra button: Research - {92780B25-18CC-41C8-B9BE-3C9C571A8263} - C:\PROGRA~1\MICROS~2\OFFICE11\REFIEBAR.DLL
O9 - Extra button: ICQ 4.0 - {B863453A-26C3-4e1f-A54D-A2CD196348E9} - C:\Program Files\ICQLite\ICQLite.exe
O9 - Extra 'Tools' menuitem: ICQ Lite - {B863453A-26C3-4e1f-A54D-A2CD196348E9} - C:\Program Files\ICQLite\ICQLite.exe
O9 - Extra button: FlashGet - {D6E814A0-E0C5-11d4-8D29-0050BA6940E3} - C:\PROGRA~1\FLASHGET\flashget.exe
O9 - Extra 'Tools' menuitem: &FlashGet - {D6E814A0-E0C5-11d4-8D29-0050BA6940E3} - C:\PROGRA~1\FLASHGET\flashget.exe
O9 - Extra button: Messenger - {FB5F1910-F110-11d2-BB9E-00C04F795683} - C:\Program Files\Messenger\MSMSGS.EXE
O9 - Extra 'Tools' menuitem: Windows Messenger - {FB5F1910-F110-11d2-BB9E-00C04F795683} - C:\Program Files\Messenger\MSMSGS.EXE
O10 - Broken Internet access because of LSP provider 'xfire_lsp_9717.dll' missing
O12 - Plugin for .spop: C:\Program Files\Internet Explorer\Plugins\NPDocBox.dll
O16 - DPF: {39B0684F-D7BF-4743-B050-FDC3F48F7E3B} (FilePlanet Download Control Class) - http://www.fileplanet.com/fpdlmgr/ca...C_1_0_0_44.cab
O16 - DPF: {6414512B-B978-451D-A0D8-FCFDF33E833C} (WUWebControl Class) - http://v5.windowsupdate.microsoft.co...?1097826489234
O16 - DPF: {70BA88C8-DAE8-4CE9-92BB-979C4A75F53B} (GSDACtl Class) - http://launch.gamespyarcade.com/soft...ch/alaunch.cab
O17 - HKLM\System\CCS\Services\Tcpip\..\{4AF8E140-D8E4-477F-A854-B38297113842}: NameServer = 192.169.34.181 203.120.90.40
O18 - Protocol: cetihpz - {CF184AD3-CDCB-4168-A3F7-8E447D129300} - C:\Program Files\HP\hpcoretech\comp\hpuiprot.dll

You appear to have a worm, and a number of other nasties that will require a genius to sort out. Hopefully Crunchie will be along soon... lol
In the meantime try using housecall to fix that worm: http://housecall.trendmicro.com/
You may also wish to scan with Panda http://www.pandasoftware.com/activescan/