I was having little trouble getting .SRT file working on Pop corn hour A-110. After some googling, I came across this page: http://www.avsforum.com/avs-vb/showthread.php?t=1060708
To enable SRT files support you need the following steps.
1. Make sure the SRT filename and the video name match (Except for the extensions obviously)
2. Make sure they are in the same directory
3. (OPTIONAL STEP) On your popcorn hour go to Setup menu, under subtitles change the language to English (Or any language, but not NONE), this will make sure the subtitles always run when you load a movie in your selected language.
4. Using your remote during playback you can enable the subtitles using the subtitles button.
Pretty simple, isn’t it?