Michael's mom said that Walt barely talks to her, and wakes up screaming in the middle of the night. This sounds like the reactions a young boy would have who was going through what Desmond and Minkowski did. Catatonic while traveling, freaked out when returning to the present.

Thoughts?

I think he's probably just traumatized by everything he experienced, which was then topped off by his father confessing to murdering two innocent women in order to save him. He's got PTSD, survivor's guilt, etc.

Just my guess.

But think, we've been seeing glimpses of Walt the whole "Month" he has been gone. We've seen him on the island at various intervals in the month, usually warning someone about something.
He could be traveling to the past in an attempt to warn the survivors. He never seems fully real. But maybe his special abilities allow him to manifest physically on some level. And if so, he got better at it with time. His specialness could make the experience of being unstuck something else entirely.

Throughout the show, I kept thinking of wet Walts backwards message about, "(don't) push the button, the button's bad" wondering how that could tie in with what we know now.

But think, we've been seeing glimpses of Walt the whole "Month" he has been gone. We've seen him on the island at various intervals in the month, usually warning someone about something.
He could be traveling to the past in an attempt to warn the survivors. He never seems fully real. But maybe his special abilities allow him to manifest physically on some level. And if so, he got better at it with time. His specialness could make the experience of being unstuck something else entirely.

Throughout the show, I kept thinking of wet Walts backwards message about, "(don't) push the button, the button's bad" wondering how that could tie in with what we know now.

I was thinking about this in reference to Walt's screaming in the middle of the night. Is the screaming somehow related to the fact that he's visited someone on the island? I'm not sure I'd consider it unstuck, cause he's not going back in time, just "visiting" someplace he is not physically.

Did Walt look like "young" Walt to anyone else? Seems like he looks like the way he used to as opposed to the way he appeared to Locke.

Did Walt look like "young" Walt to anyone else? Seems like he looks like the way he used to as opposed to the way he appeared to Locke.

Yes he looked more like Walt from younger days as opposed to the tall ghost Walt that chatted with Locke in the pit. It really stood out for me when they showed it, but it was flashed too fast so I went back to the screen cap after.. and proceeded to make a 3 way Walt image of Season 1, the window, and "tall ghost" Walt.
3 Faces of Walt (http://img.photobucket.com/albums/v336/elpack/walt03.jpg)

I'm thinking that window Walt doesn't look much older than Season 1 Walt.. but Pit standing Walt is at an upward angle making it appear he's much taller than the other images.. so I'm not sure what I think about his size..

I don't think he's stuck or unstuck in time at this point.. what I think is that for a young kid, he's been through a whole lot and isn't even able to discuss what really happened to him to anyone... and that's got to be extremely traumatic, emotional, and more than enough reason to be completely screwed up.. oh and his dad is a murderer.. and he knows that others are alive but presumed dead.. and etc... so I don't think time has anything to do with his nightmares, or anything.. it's just what he's been through.