Intimidate lets you copy any first 1st and 2nd class skill that has inflicted direkt damage on you, like Raging Trifecta Blow and Bowling Bash, probably the two most popular leveling skills for Rogues and Stalkers. But as soon as you are hit with another skill fit for Intimidate, the skill you previously used is now replaced.
Preserve is a stalker skill only and it lets you, like the name says, preserve the skill you have copied with Intimidate. It's an active skill so you have to keep an eye out for the little icon on the right indicating if it's on or not.
The problem: Preserve turns itself off all the time without you ever knowing it.
Step into a warp to go to Magmarings? Preserve turn off, you arrive, might be hit by a Droseras Pierce lv 5 and now they skill you wanted to save is gone before you even have the time to turn Preserve back on.
Walk into another map, Sometimes and sometime not, preserve will turn itself of, depends on what map you left from, I turned on preserve when I walked from Prontera down to Poring Island, cleared the first map change and preserve was still active, but when I changed map from the desert to poring island, it turned itself off, and I didn't notice this, and thus my skill got lost to Ghostring.
I've tried solving this, I put an eggclock on my desk for 5min, just for the purpose of recharging Preserve, which skill time is 10min, but still, I manange to lose the skill multiple times a day.
I mean, c'mon should I really have to have an egg clock to make sure I rememember to put Preserve on? That's not fun.
The solution could be just to make sure it doesn't turn off every time you change area, or even better, make it Toggleable, like Reproduce.
Once you've activated the skill, your copied skill won't be replaced unless you toggle the skill again or maybe relog.
Screenshots.
Before map change:

After map change:

This might not seem like a big problem to some of you, but it is, it's extremely annoying trying to reacquire skill such as Bowling Bash unless you have a knight friend available, and for what? Because you walked from one map to the next? Even if you try to use Preserve right at the door when you change map, there might be aggresive monsters.
So, please do all us Rogue classed players a favor, improve preserve.