OK!
Questo è quanto mi è ricomparso al riavvio:
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Avenger Pre-Processor log
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Platform: Windows XP (build 2600, Service Pack 2)
Tue Mar 25 11:05:55 2008

11:05:55: Error: Invalid script. A valid script must begin with a command directive.
Aborting execution!


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Logfile of The Avenger Version 2.0, (c) by Swandog46
http://swandog46.geekstogo.com

Platform: Windows XP

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Script file opened successfully.
Script file read successfully.

Backups directory opened successfully at C:\Avenger

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Beginning to process script file:

Rootkit scan active.
No rootkits found!

File "C:\DOCUME~1\x\IMPOST~1\Temp\jqwjhdqa.exe" deleted successfully.
File "C:\DOCUME~1\x\IMPOST~1\Temp\9v7av45g.exe" deleted successfully.
File "C:\DOCUME~1\x\IMPOST~1\Temp\removefiles.txtte mp" deleted successfully.

Completed script processing.

*******************

Finished! Terminate.

Inoltre, il problema della finestra security all'avvio persiste.
Prima di avviare ccleaner ti ricordo che il file che mi hai segnalato da eliminare dal registro non c'è.