Trojan Horse Downloader : Dyfica.2.2BA inflected = Need Help

Archived from groups: microsoft.public.win2000.security (More info?)

Dear All,

My friend's computer inflected by following Torjan Horse !
(scanned by Ad-Aware)

Trojan Horse Downloader : Dyfica.2.BA

inflect files :

C:\System Volume Information\_restore{.....}.....\A1604249.dll
C:\System Volume Information\_restore{.....}.....\A1604330.dll
C:\System Volume Information\_restore{.....}.....\A1604404.dll
C:\System Volume Information\_restore{.....}.....\A1604455.dll
C:\System Volume Information\_restore{.....}.....\A1604456.dll

Trojan Horse Downloader : Small.20.U

Can you please advise how to clean it ?

Many thx for your advise