There may be a 4th option...
I was having the same problem with the Send Mail function. I use FM4.0 under Win2K and Outlook 2000, and the script was intermittent - sometimes it created the mail message, sometimes it didn't bother.
I added a Show Message command after the Send Mail command (so the users could say whether it worked or not and re-run the script if it didn't) and since then it's worked every time!
Cheaper than the upgrade to v 5....