This is related to the hardware just like in the 6700, its done w/ magnets... here is something try if you don't believe me. Take a fairly strong magnet and while your keyboard is out just slide it over the screen(top to bottom). your screen will change to portrait ..and then back to landscape....This issue has been discussed many time in apache and the titan forums as well as other web sites......there's an exe file out there called landscaper that allows the phone to always switch to landscape mode. When you wake the phone up or slide the keyboard the screen will change back to portrait but only briefly (you can set the amount of time in the options menu, if you set it to 0 its pretty quick that it goes back to landscape). You will have to either put it in the start up folder or manually start the program each time after a soft reset. I personally just decided on mapping a hard key to rotate the screen and find this easier and quicker. check it out, below
http://forum.xda-developers.com/showthread.php?t=329467