For those who do not know Donna MVP's Blog:
"When Microsoft released Internet Explorer 8… IE8 will freeze and/or use 100% CPU usage if IE8 has been immunized. The issue is now fixed as per Spybot-S&D Team:
Update: Microsoft finally released a fix for this issue. The update has been released on June 9th. If you experienced problems with IE8 and Spybot's immunization, please download the update "KB969897" via the Windows updates or download your copy directly at Microsoft."
More:
IE8 issue when immunized by Spybot-S&D is now fixed - Donna's SecurityFlash