dust.exe is a peer-to-peer worm.
if u have kaazza, etc installed, u cud b affected. suggest u schedule a boot-time scan of avast anti-virus or run your anti-virus in safe mode.
check out
*www.bullguard.com/forum/9/dustexe-virus-what-is-it_550.html
*www.dslreports.com/forum/remark,12346925~mode=flat