Windows XP Update Agent Takes Over The Machine

Microsoft has known issue in Auto Update Agent when wuauclt.exe takes 100% of CPU. It can cause that notification icon will not be shown. Here is solutiuon which works for me. Open Console and enter these commmands one by one:

net stop bits 
net stop wuauserv 
regsvr32 /u wuaueng.dll /s
del /f /s /q %windir%\SoftwareDistribution\*.*
del /f /s /q %windir%\windowsupdate.log
regsvr32 wuaueng.dll /s
net start bits
net start wuauserv
wuauclt.exe /resetauthorization /detectnow

After these steps leave computer running for one hour. Notification icon should appear. ;)