OK, about this 'puter:
. Windows XP home, service pack 3

. Firefox 3.5.7

. Spybot S&D 1.6.2.0, last updated on or about 02/05/10

. false positive occurred while applying the Avast 5.0.396 program update

. Spybot S&D log file:
2/7/2010 1:17:27 PM Allowed (based on user decision) value "NoDriveAutoRun" (new data: "hex:F0,03,00,") changed in System Startup user entry!
2/7/2010 1:17:28 PM Allowed (based on user decision) value "NoRecentDocsMenu" (new data: "hex:01,00,00,") changed in System Startup user entry!
2/7/2010 1:17:28 PM Allowed (based on user decision) value "NoRecentDocsHistory" (new data: "hex:01,00,00,") changed in System Startup user entry!
2/7/2010 1:24:41 PM Allowed (based on user decision) value "avast!" (new data: "") deleted in System Startup global entry!
2/7/2010 1:25:47 PM Allowed (based on user decision) value "avast5" (new data: "C:\PROGRA~1\ALWILS~1\Avast5\avastUI.exe /nogui") added in System Startup global entry!
2/7/2010 1:25:47 PM Encountered and terminated DoubleD.DesktopSmiley in C:\WINDOWS\system32\msiexec.exe!
2/7/2010 1:33:13 PM Allowed (based on user decision) value "NoDriveAutoRun" (new data: "hex:F0,03,00,") changed in System Startup user entry!
2/7/2010 1:33:14 PM Allowed (based on user decision) value "NoRecentDocsMenu" (new data: "hex:01,00,00,") changed in System Startup user entry!
2/7/2010 1:33:14 PM Allowed (based on user decision) value "NoRecentDocsHistory" (new data: "hex:01,00,00,") changed in System Startup user entry!