I experience this same behavior with my almost 8 month old... and I chalk it up to teething and new-found power (to cry and get me to respond). She naps ok most of the time, but only if I lie down next to her on my bed. I end up putting pillows all around her and letting her sleep, either staying in the room with her or staying very close by so that she doesn't wake up and start crawling off the bed.
I'm having the EXACT same problem you describe, though, at night when I go to put her in her crib. It's almost as if she's worried that I'm never coming back, or that she's missing something important in the living room while she's confined to her crib. sigh. She will repeatedly pull herself up and cry, no matter how many times I lay her back down and giver her a lovey to hold and put the paci in. It's getting very trying. This has only been happening for about 2 weeks. My husband usually arrives home about the time she's going to bed, so he takes over and sits with her (I think she's too attached to me and that's part of the problem when it comes to sleeping). And yes, I'm sure that she's tired and ready to go to bed. And yes, she's napped appropriately during the day, so she's not more tired. And yes, we've given her tylenol and/or orajel for teething before bed.
Sleep issues are the bane of my existence right now. The only thing getting me through it is that I know it won't last forever.
Good luck to you, too... and know you're not alone!