Thanks for the info. That's quite helpful since msconfig doesn't run on the computer (W2K).
I ran the free online virus scan on Trend Micro
. It found 7 infected files, including BKDR_IROFFER, IRC_BOUNCE, TROJ_HIDEWND, TROJ_FLOOD.C. They were digusted as vm32.exe. winclock.exe and smnt.exe.
(Norton with the most updated virus signature couldn't find those infected files)
After the scan and removal, no more mIRC autostart problem anymore.