My mistake, turns out I'd forgotten to upgrade to 6.14 on my XP system. The bug is present in XP Home (although 98SE is unaffected). Also strange things with using pipe:
Get a 'Cannot create file...' error when trying to /write to 'pipe.conf'. Also, /mkdir pipe returns an error, but still creates the folder. And $isdir(pipe) will return $false, however $isdir(pipe\) will return $true. Bizarre.