Thanks Zoti! You know I really thought I had it all the way back, but when the problem stopped I figured I hadn't. My other pistol has a little half-moon where the spring seats in the middle, so I may not have had it lined up properly.I have the same problem sometimes. I think it's the spring not seating correctly even though I have aligned it correctly. If you rack it a couple of times when it gives you the problem it will eventually pop into place and then the slide will move far enought so you can use the slide stop lever to lock it back.