In addition to what has been posted above, an analysis of your HJT log shows the following problems :
O2 - BHO: (no name) - {0CA2FA2F-4BAF-4CFF-9EB3-C5856AF87F2A} - C:\WINDOWS\system32\xxyaabbb.dll (file missing)
Part of Spyware group - SpywareQuake. Unnecessary (deactivated) entry that can be fixed.
http://spywaredlls.prevx.com/RRIIJF44771343/XXYAABBB.DLL.html
O2 - BHO: AVG Safe Search - {3CA2F312-6F6E-4B53-A66E-4E65E497C8C0} - C:\Program Files\AVG\AVG8\avgssie.dll (file missing)
Unnecessary (deactivated) entry that can be fixed. LinkScannerIE.dll
O2 - BHO: AVG Security Toolbar - {A057A204-BACC-4D26-9990-79A187E2698E} - C:\PROGRA~1\AVG\AVG8\AVGTOO~1.DLL (file missing)
Unnecessary (deactivated) entry that can be fixed. avgtoolbar.dll
O3 - Toolbar: AVG Security Toolbar - {A057A204-BACC-4D26-9990-79A187E2698E} - C:\PROGRA~1\AVG\AVG8\AVGTOO~1.DLL (file missing)
Unnecessary (deactivated) entry that can be fixed. avgtoolbar.dll, AVGTOO~1.DLL - AVG “Anti-Exploit” Toolbar, present in AVG8.
O4 - Startup: ikowin32.exe
Very BAD entry - Cloaked Malware.
http://www.prevx.com/filenames/X86670579050249676-X1/IKOWIN32.EXE.html
Also related to Trojan.Virantix.C, XP Antispyware 2009, and braviax.
http://www.precisesecurity.com/files-process/2009/08/20/ikowin32exe/
O18 - Protocol: linkscanner - {F274614C-63F8-47D5-A4D1-FBDDE494F8D1} - C:\Program Files\AVG\AVG8\avgpp.dll (file missing)
Unnecessary (deactivated) entry that can be fixed.
I also suggest you use MBAM as did Yokenny.
Overview of running tasks :
smss.exe
System task
Session Manager Subsystem
winlogon.exe
System task
Microsoft Windows Logon Process
services.exe
System task
Windows Service Controller
lsass.exe
System task
Local Security Authority Service
svchost.exe
System task
Microsoft Service Host Process
svchost.exe
System task
Microsoft Service Host Process
vsmon.exe
Firewall
ZoneLabs True Vector Internet Monitor
Explorer.EXE
System task
Microsoft Windows Explorer
aswUpdSv.exe
Virusscan
Avast Anti-Virus Component
AAWService.exe
Anti Add/Spyware software
Ad-Aware 2007 Service
ashServ.exe
Virusscan
Avast
spoolsv.exe
System task
Microsoft Printer Spooler Service
AppleMobileDeviceService.exe
Backgroundtask
Apple Mobile Device Service
mDNSResponder.exe
Backgroundtask
Bonjour for Windows Component
MDM.EXE
Backgroundtask
Machine Debug Manager
SMARTBoardService.exe
Backgroundtask
SMARTBoardService (SMART Board is an interactive whiteboard application that can be used over a LAN or the Internet.)
svchost.exe
System task
Microsoft Service Host Process
ashMaiSv.exe
Virusscan
Avast Anti-Virus Component
ashWebSv.exe
Virusscan
avast! Web Scanner
smax4pnp.exe
Application
Soundmax agent
lxccmon.exe
Backgroundtask
Lexmark 3300 Series Device Monitor
hkcmd.exe
Application
Intel multimedia devices
igfxpers.exe
Driver
Intel Common User Interface Module
ashDisp.exe
Virusscan
Avast AntiVirus
AAWTray.exe
Backgroundtask
AAWTray Application
zlclient.exe
Firewall
ZoneLabs Firewall Client
realsched.exe
Application
RealNetworks Scheduler
QTTask.exe
Backgroundtask
Apple QuickTime Tray Icon
iTunesHelper.exe
Application
Apple Itunes
ctfmon.exe
System task
Alternative User Input Services
EasyShare.exe
Backgroundtask
Software bundled with Kodak digital cameras to manage the connection between the PC and the Camera.
SetPoint.exe
Backgroundtask
Logitech SetPoint Event Manager
lxcccoms.exe
Unknown task
Unknown task (Comms Application for Lexmark)
SMARTBoardTools.exe
Unknown task
Unknown task (part of SMART Board)
KHALMNPR.EXE
Backgroundtask
Logitech Mouse Utility
iPodService.exe
Backgroundtask
Apple iTunes
Aware.exe
Unknown task
Unknown task (part of SMART Board)
Marker.exe
Unknown task
Unknown task (part of SMART Board)
firefox.exe
Application
Mozilla Firefox
HijackThis.exe
Application
Merijn Hijackthis