has anyone had problems with these crampons coming loose? mine came loose several times and i wonder if they were not adjusted properly or something. boots are la sportiva lhotse.

Attaching crampons less-than-securely seems to be relatively commonplace. Spend some time indoors with the boots you intend to use them on and make sure you get a positive fit with the sole squarely within the metal brackets at the heel. Fitting it this closely may mean that you can't actually step into the crampon without using the heel lever to shove the boot forward that last little bit, but the security is worth the effort.

Make sure that you have the heel piece set tight enough, they should snap into place when you're putting them on and put up moderate resistance when taking them off. Try moving the pieces closer to each other by a hole and fiddle around with the fit before you head out next time. Its easier to play with crampons when it's not freezing out. I've stepped out of my crampons exactly once, and it was because I hadn't snapped them into the correct spot on the heel of my boot. Double check when you put them on that they seat correctly.

You shouldn't have a problem with these...I use mine on ski boots and mountaineering boots and, properly adjusted, they stay on great.