This is a hard thing to explain, but I'll give it a shot. I've been following a pattern that has a lot of m1 in it - Diamante Socks from Knitty.com. The pattern is most definitely not the problem though.
After knitting about half the sock, I'm at the heel now, I started losing a st and figured out it was at my m1. This is the "lift from front to back and knit into back loop" m1. What I sometimes do is if I miss the knit (the needle slips out when trying to knit through the back loop) it seems to pull out the previous st I knit from the right-hand needle. Took me a while to figure out, because I was losing sts, but nothing was unraveling down (still haven't figured that one out).
Once I finally figured out what was happening, I'm extra careful, and if I miss that st I recount everything to make sure I haven't lost anything. Thing is, I can't figure out how to fix this once it's happened and I move on. If the st would unravel like any other dropped st, then that would be easy, but it doesn't seem to. I have to let go of my m1 loop, then I kind of see the st I dropped, but it doesn't look right after I fix it like other dropped sts.
Geez, that doesn't seem to make sense, but I hope someone will understand what I'm trying to say and help me find a way to fix it properly. As careful as I've been, it's happened a couple of time since.