Dang, you beat me to it, that's pretty much what I was going to say. I had to figure it out the hard way, though, by having long compiles and jumpy motion and then figuring out how to solve the problem.
I thought I would state the obvious, though. Make a single step first, copy it, and use the "paste special' function to create multiple copies that are offset from each other.. voila, a staircase! With a bit of ingenuity you can even use paste special to make a curved staircase or spiral stairs, though I've decided that it's usually more trouble than it's worth.
You can make a spiral staircase fairly simply with this tutorial: Spiral Stairs Tutorial
ONLY IF YOU LEAVE "TEXTURE LOCK" ON. to solve this, press the 'tl' button at the top of the screen (so that it isnt toggled) then use shift+click and drag to copy them.A note if you copy and paste one step to make another, and so on; if you look at your steps head on or from above you'll notice the texture is identical for every step.. This is just something i have grown to hate because the steps look blatently cloned. Give them a little scroll with your texture tool adjusting the texture scrolling by perhaps 20-30 untis either way... then your steps will all look individual.
I'll post a screen shot later demonstrating.. unless you understand without screens?