Impossible d'installer un antivirus

Bonjour tout le monde;
j'ai 3 PC en réseau mes problèmes sont :
-Pas d'accès à la base de registre
-Pas d'accès au gestionnaires des tâches
-Installation d'un antivirus est impossible
Voilà les rapports de HijackThis

-Poste1
Logfile of Trend Micro HijackThis v2.0.2
Scan saved at 14:22:15, on 27/10/2011
Platform: Windows XP SP2 (WinNT 5.01.2600)
MSIE: Internet Explorer v6.00 SP2 (6.00.2900.2180)
Boot mode: Normal

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\Explorer.EXE
C:\WINDOWS\system32\spoolsv.exe
C:\Program Files\Java\j2re1.4.2_05\bin\jusched.exe
C:\Program Files\Hewlett-Packard\Toolbox2.0\Apache Tomcat 4.0\webapps\Toolbox\StatusClient\StatusClient.exe
C:\Program Files\Lexmark 7300 Series\lxcimon.exe
C:\Program Files\Lexmark 7300 Series\ezprint.exe
C:\Program Files\Modem Samsung SCH-U209\sysctrlU.exe
C:\Program Files\Modem Samsung SCH-U209\SamsungPnPServiceManager.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\system32\lxcicoms.exe
G:\HiJackThis.exe

R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Default_Page_URL = http://go.microsoft.com/fwlink/?LinkId=69157
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Default_Search_URL = http://go.microsoft.com/fwlink/?LinkId=54896
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Search Page = http://go.microsoft.com/fwlink/?LinkId=54896
R0 - HKCU\Software\Microsoft\Internet Explorer\Toolbar,LinksFolderName = Liens
O2 - BHO: (no name) - {FFFFFEF0-5B30-21D4-945D-000000000000} - C:\PROGRA~1\STARDO~1\SDIEInt.dll
O3 - Toolbar: &Radio - {8E718888-423F-11D2-876E-00A0C9082467} - C:\WINDOWS\system32\msdxm.ocx
O3 - Toolbar: Star Downloader Toolbar - {8CEB3591-5DDC-47ec-AF97-66699BC85FE0} - C:\Program Files\Star Downloader Toolbar\v2.0.0.5\Star_Downloader_Toolbar.dll
O4 - HKLM\..\Run: [NeroFilterCheck] C:\WINDOWS\system32\NeroCheck.exe
O4 - HKLM\..\Run: [SunJavaUpdateSched] C:\Program Files\Java\j2re1.4.2_05\bin\jusched.exe
O4 - HKLM\..\Run: [StatusClient] C:\Program Files\Hewlett-Packard\Toolbox2.0\Apache Tomcat 4.0\webapps\Toolbox\StatusClient\StatusClient.exe /auto
O4 - HKLM\..\Run: [TomcatStartup] C:\Program Files\Hewlett-Packard\Toolbox2.0\hpbpsttp.exe
O4 - HKLM\..\Run: [LXCICATS] rundll32 C:\WINDOWS\System32\spool\DRIVERS\W32X86\3\LXCItime.dll,_RunDLLEntry@16
O4 - HKLM\..\Run: [lxcimon.exe] "C:\Program Files\Lexmark 7300 Series\lxcimon.exe"
O4 - HKLM\..\Run: [EzPrint] "C:\Program Files\Lexmark 7300 Series\ezprint.exe"
O4 - HKCU\..\Run: [Z810SysStart] C:\Program Files\Modem Samsung SCH-U209\sysctrlU.exe
O4 - HKCU\..\Run: [Z810PNP] C:\Program Files\Modem Samsung SCH-U209\SamsungPnPServiceManager.exe
O7 - HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\System, DisableRegedit=1
O8 - Extra context menu item: Download with Star Downloader - C:\Program Files\Star Downloader\sdie.htm
O8 - Extra context menu item: E&xporter vers Microsoft Excel - res://C:\PROGRA~1\Microsoft Office\OFFICE11\EXCEL.EXE/3000
O9 - Extra button: (no name) - {08B0E5C0-4FCB-11CF-AAA5-00401C608501} - C:\Program Files\Java\j2re1.4.2_05\bin\npjpi142_05.dll
O9 - Extra 'Tools' menuitem: Console Java (Sun) - {08B0E5C0-4FCB-11CF-AAA5-00401C608501} - C:\Program Files\Java\j2re1.4.2_05\bin\npjpi142_05.dll
O23 - Service: hdlSrv - Unknown owner - C:\Program Files\M-Systems Utility\hdlSrv.exe
O23 - Service: lxci_device - - C:\WINDOWS\system32\lxcicoms.exe
O23 - Service: Pml Driver HPZ12 - HP - C:\WINDOWS\system32\HPZipm12.exe