Make a shortcut, or change from the "Run" menu in the startmenu, so it looks like this:
C: \Sierra\Half-Life\hl.exe -console -game esf
If you cant figure that out, try opening HL normally. When you have done so, select the menu on the third from the bottom selection, and it should be called something like "Mod Viewer" or something like that. Find ESF, and run it from there.
If nothing of this works, there is a slim chance you have the same error i had one time.
C:/Sierra/Half-Life/hl.exe -console -game esf
Try changing the backslashes to normal slashes