I've used the Windows serial port drivers fairly extensively, and haven't run into this problem. Does this problem occur at other baud rates? And have you checked that you're running the latest version of
Win32::SerialPort? I'm running under NT, which (IMHO) has better support than Win95/98.
I ran your code, and had no problems, trying a number of baud rates and reboot combinations (which takes a dang long time with 256MB of memory, and 4 SCSI devices on the chain...).
--Chris
e-mail jcwren