Share your experience!
Just got the SE Xperia X10, I'm not sure what I click but it won't go to landscape anymore when I text. I really prefer texting in landscape mode. I just got the phone 3 days ago. I installed juice defender and task killer, I'm not sure if it has any thing to do with that... HELP ME PLEASE!!!!!!
Hello.
When you start composing your message in upright mode just turn the phone to landscape and after a second the screen will turn landscape too.
That's the thing it use to do it, but now it won't... 
In Menu, Settings, Sound and Display is your Orientation box checked?
If it isn't... tick it.
If it already is, try unticking, turn phone off then back on and go back and retick and see if it sorts itself out.
Are you using the stock SMS app? Maybe try downloading an app if you have access to market. Handcent is quite good. (Again if you are using an app check the settings on that as Handcent has its own orientation tick box)
i was just having the same issue! i checked the orientation mode in sounds and display. it works...