PEN DRIVE HIDE FOLDERS

CLICK ON START SELECT RUN->cmd (COMMAND PROMPT)

change to the pendrive drive, i.e. g:

type "dir/ah"

if u see something like autorun.inf, xysy.cmd, lslsls.exe then u got virus

also can manually remove them:

type "attrib -s -h *.*"

then manually delete those viruses.