What am I doing wrong?"
Answer: you are probably doing everything right. The textboxes for the songs are not 100% compatible with every browser, so the copy into the clipboard will sometimes take on html or other garbage.
The best work around is: after you copy the song use the 3ml editor to import from the clipboard. That will parse out the junk that came along with the copy. At that point you can copy chord for chord or use F7 to copy a clean block into the clipboard for composing in Mabi.
The 2nd best work around is to copy the song out and paste it into a notepad. Once there you can parse it manually by removing the MML@ tag and separating the chords at the commas.
On a personal note, I am still outt of work. I am looking at being kicked out of my apartment and out into the street. If any of you have favors to call in from demi-gods or deities, a prayer of mercy on me would not go amiss - I would even accept blessings from the not-so-nice gods at this point. Despiration