Look, this happens to me all the time. I write a song, and figure out I jipped it from somebody. It's usually either Blink-182, Green Day, and Rise Against sometimes. And theres no way you can do anything in music without it being done. You make a chord progression and it's probably already been done. But it's also easy to tweak it and make it your own but at the same time have people see your influence. The whole idea with going to court is dumb. The only way thats going to happen is if you really stole the song, i.e. taking the same lyrics and chords. Trust me I've done a lot of stuff and it's been taken from other artists but I tweak and its fine. But it was funny, my guitar teachers was the guitarists at a wedding, and he was playing this really nice song he wrote, and then after the ceremony this guy comes up to him and says, "That's an odd variation of "Blackbird", but I liked it. =)" And he was just thinking Oh ****... lol. See theirs a difference, if you tweak it so it isn't the song with a different variation it's ok, of course if you do it on accident like my teacher its fine, less you "accidentally" steal the lryics ;);). And don't worry, no band is going to sue you for accidentally tweaking their tune. :P