用HijackThis扫描你的系统．发个日志上来看看

HijackThis V1.99.1 完全汉化版下载
http://forum.ikaka.com/download.asp?id=5984255

F3 - REG:win.ini: load=C:\WINDOWS\inf\rundll32.exe
O2 - BHO: ThunderIEHelper Class - {0005A87D-D626-4B3A-84F9-1D9571695F55} - C:\WINDOWS\system32\xunleibho_v5.dll
O2 - BHO: NaviHelperObj Class - {3E422F49-1566-40D3-B43D-077EF739AC32} - C:\WINDOWS\system32\NaviHelper.dll (file missing)
O2 - BHO: IeCatch2 Class - {A5366673-E8CA-11D3-9CD9-0090271D075B} - C:\PROGRA~1\FLASHGET\jccatch.dll
O2 - BHO: AssistII - {BB936323-19FA-4521-BA29-ECA6A121BC78} - C:\PROGRA~1\3721\Assist\asbar.dll
O2 - BHO: IE - {D157330A-9EF3-49F8-9A67-4141AC41ADD4} - C:\WINDOWS\downlo~1\CnsHook.dll
O3 - IE工具栏增项: FlashGet Bar - {E0E899AB-F487-11D5-8D29-0050BA6940E3} - C:\PROGRA~1\FLASHGET\fgiebar.dll
O3 - IE工具栏增项: 上网助手 - {BB936323-19FA-4521-BA29-ECA6A121BC78} - C:\PROGRA~1\3721\Assist\asbar.dll
O4 - 启动项HKLM\\Run: [PHIME2002ASync] C:\WINDOWS\System32\IME\TINTLGNT\TINTSETP.EXE /SYNC
O4 - 启动项HKLM\\Run: [PHIME2002A] C:\WINDOWS\System32\IME\TINTLGNT\TINTSETP.EXE /IMEName
O4 - 启动项HKLM\\Run: [NvCplDaemon] RUNDLL32.EXE C:\WINDOWS\System32\NvCpl.dll,NvStartup
O4 - 启动项HKLM\\Run: [nwiz] nwiz.exe /install
O4 - 启动项HKLM\\Run: [CnsMin] Rundll32.exe C:\WINDOWS\downlo~1\CnsMin.dll,Rundll32
O4 - 启动项HKLM\\Run: [Logitech Utility] Logi_MwX.Exe
O4 - 启动项HKLM\\Run: [RavTimer] C:\PROGRA~1\RISING\RAV\RAVTIMER.EXE
O4 - 启动项HKLM\\Run: [RavMon] C:\PROGRA~1\RISING\RAV\RAVMON.EXE -SYSTEM
O4 - 启动项HKLM\\Run: [RfwMain] "C:\Program Files\Rising\Rfw\rfwmain.exe" -Startup
O4 - 启动项HKLM\\Run: [BigDogPath] C:\WINDOWS\VM_STI.EXE USB PC Camera 301P
O4 - 启动项HKLM\\Run: [MINI_BFYY] C:\Program Files\Ringz Studio\Storm Downloader\StormDownloader.exe
O4 - 启动项HKLM\\Run: [StormCodec_Helper] "C:\Program Files\Ringz Studio\Storm Codec\StormSet.exe" /S /opti
O4 - 启动项HKLM\\Run: [TkBellExe] "C:\Program Files\Common Files\Real\Update_OB\realsched.exe"  -osboot
O4 - 启动项HKLM\\Run: [helper.dll] C:\WINDOWS\system32\rundll32.exe C:\PROGRA~1\3721\helper.dll,Rundll32
O4 - 启动项HKLM\\Run: [UserFaultCheck] %systemroot%\system32\dumprep 0 -u
O4 - HKCU\..\Run: [ctfmon.exe] C:\WINDOWS\system32\ctfmon.exe
O4 - HKCU\..\Run: [msnmsgr] "C:\Program Files\MSN Messenger\msnmsgr.exe" /background

O8 - IE右键菜单中的新增项目: !搜一搜 - res://C:\WINDOWS\downlo~1\CnsMinEx.dll/1003
O8 - IE右键菜单中的新增项目: &使用暴风下载器下载 - C:\Program Files\Ringz Studio\Storm Downloader\geturl.htm
O8 - IE右键菜单中的新增项目: &使用迅雷下载 - D:\Thunder\geturl.htm
O8 - IE右键菜单中的新增项目: &使用迅雷下载全部链接 - D:\Thunder\getAllurl.htm
O8 - IE右键菜单中的新增项目: 使用Kugoo下载 - D:\KUGOO2\KugooDownX.htm
O8 - IE右键菜单中的新增项目: 使用网际快车下载 - C:\Program Files\FlashGet\jc_link.htm
O8 - IE右键菜单中的新增项目: 使用网际快车下载全部链接 - C:\Program Files\FlashGet\jc_all.htm
O8 - IE右键菜单中的新增项目: 添加到QQ自定义面板 - D:\QQ\AddPanel.htm
O8 - IE右键菜单中的新增项目: 添加到QQ表情 - D:\QQ\AddEmotion.htm
O8 - IE右键菜单中的新增项目: 用QQ彩信发送该图片 - D:\QQ\SendMMS.htm
O8 - IE右键菜单中的新增项目: 解霸实时播放 - C:\HEROSOFT\Hero3000\MPURLGET.HTM
O9 - 浏览器额外的按钮: 手机短信 - {00000000-0000-0001-0001-596BAEDD1289} - http://sms.3721.com/ie/index.htm?pid=U_3721home (file missing)
O9 - 浏览器额外的按钮: 浩方对战平台 - {0A155D3C-68E2-4215-A47A-E800A446447A} - E:\浩方对战平台\GameClient.exe
O9 - 浏览器额外的按钮: 解霸 - {367E0A21-8601-4986-9C9A-153BF5ACA118} - C:\HEROSOFT\Hero3000\MPLAYER.EXE
O9 - 浏览器额外的“工具”菜单项: 超级解霸 - {367E0A21-8601-4986-9C9A-153BF5ACA118} - C:\HEROSOFT\Hero3000\MPLAYER.EXE
O9 - 浏览器额外的按钮: Yahoo 1G电邮 - {507F9113-CD77-4866-BA92-0E86DA3D0B97} - http://cn.mail.yahoo.com/promo/rd1 (file missing)
O9 - 浏览器额外的按钮: 寻宝乐趣多 - {59BC54A2-56B3-44a0-93E5-432D58746E26} - http://hot.3721.com/rd/shop_btn.htm (file missing)
O9 - 浏览器额外的按钮: 上网助手 - {5D73EE86-05F1-49ed-B850-E423120EC338} - http://assistant.3721.com/index.htm?fb=Cns (file missing)
O9 - 浏览器额外的按钮: QQ - {c95fe080-8f5d-11d2-a20b-00aa003c157b} - d:\QQ\QQ.EXE
O9 - 浏览器额外的“工具”菜单项: 腾讯QQ - {c95fe080-8f5d-11d2-a20b-00aa003c157b} - d:\QQ\QQ.EXE
O9 - 浏览器额外的按钮: FlashGet - {D6E814A0-E0C5-11d4-8D29-0050BA6940E3} - C:\PROGRA~1\FLASHGET\flashget.exe
O9 - 浏览器额外的“工具”菜单项: &FlashGet - {D6E814A0-E0C5-11d4-8D29-0050BA6940E3} - C:\PROGRA~1\FLASHGET\flashget.exe
O9 - 浏览器额外的按钮: 易趣购物 - {DE60714F-AC19-427e-861A-FD60ABDF119A} - http://click2.ad4all.net/url2/urlmanage/url.asp?id=1 (file missing)
O9 - 浏览器额外的“工具”菜单项: 易趣购物 - {DE60714F-AC19-427e-861A-FD60ABDF119A} - http://click2.ad4all.net/url2/urlmanage/url.asp?id=1 (file missing)
O9 - 浏览器额外的按钮: 情景聊天 - {E5D12C4E-7B4F-11D3-B5C9-0050045C3C96} - http://cn.rd.yahoo.com/home/messenger/bjk/clientbtn/?http://cn.messenger.yahoo.com/ (file missing)
O9 - 浏览器额外的按钮: (no name) - {ECF2E268-F28C-48d2-9AB7-8F69C11CCB71} - http://assistant.3721.com/security1.htm?fb=Cns (file missing)
O9 - 浏览器额外的“工具”菜单项: 修复浏览器 - {ECF2E268-F28C-48d2-9AB7-8F69C11CCB71} - http://assistant.3721.com/security1.htm?fb=Cns (file missing)
O9 - 浏览器额外的按钮: Messenger - {FB5F1910-F110-11d2-BB9E-00C04F795683} - C:\Program Files\Messenger\msmsgs.exe
O9 - 浏览器额外的“工具”菜单项: Windows Messenger - {FB5F1910-F110-11d2-BB9E-00C04F795683} - C:\Program Files\Messenger\msmsgs.exe
O9 - 浏览器额外的按钮: (no name) - {FD00D911-7529-4084-9946-A29F1BDF4FE5} - http://assistant.3721.com/clean1.htm?fb=Cns (file missing)
O9 - 浏览器额外的“工具”菜单项: 清理上网记录 - {FD00D911-7529-4084-9946-A29F1BDF4FE5} - http://assistant.3721.com/clean1.htm?fb=Cns (file missing)
O11 - Options group: [!CNS]  上网助手-地址栏搜索
O16 - DPF: {0CA54D3F-CEAE-48AF-9A2B-31909CB9515D} (Edit Class) - https://www.sz1.cmbchina.com/download/CMBEdit.cab
O16 - DPF: {2354A44B-3CEB-4829-9940-545B03103538} (PowerPlr Control) - http://bbsky.wuhan.net.cn/htyy/plugin/PowerPlr.ocx
O16 - DPF: {6414512B-B978-451D-A0D8-FCFDF33E833C} (WUWebControl Class) - http://v5.windowsupdate.microsoft.com/v5consumer/V5Controls/en/x86/client/wuweb_site.cab?1115110410346
O16 - DPF: {F2EB8999-766E-4BF6-AAAD-188D398C0D0B} (PBActiveX40 Control) - http://www4.cmbchina.com/download/pb45.cab
O17 - HKLM\System\CCS\Services\Tcpip\..\{F767B558-573A-4413-9559-CEEA7019AE75}: NameServer = 202.103.0.117 202.103.24.68
O23 - NT 服务: NVIDIA Display Driver Service (NVSvc) - NVIDIA Corporation - C:\WINDOWS\System32\nvsvc32.exe
O23 - NT 服务: Rising Personal Firewall Service (RfwService) - Beijing Rising Technology Corporation Limited - c:\program files\rising\rfw\rfwsrv.exe
O23 - NT 服务: Rising Process Communication Center (RsCCenter) - rising - C:\PROGRAM FILES\RISING\RAV\CCENTER.EXE
O23 - NT 服务: RsRavMon Service (RsRavMon) - Beijing Rising Technology Co., Ltd. - C:\PROGRAM FILES\RISING\RAV\Ravmond.exe

日志上看并无问题．
你只要用HijackThis修复Ｆ３项即可
或者在开始－＞运行中输入msconfig.然后在启动项中取消REG:win.ini: load=C:\WINDOWS\inf\rundll32.exe这一项的钩选.