Hi All,
I am not sure if my problem is related or not but here goes...!!
I have the original EVO4G and so does my wife, both stock and not rooted. We have all the current updates except the last one (didn't care for the signal manager or what ever it's called).
Anyway just recently we noticed when we texted each other the phone would reverse the the conversation, in other word's I woud send a text to her and when she replied the reply would apear ABOVE mine instead of below it.
So we were at the Braves Game (GO BRAVES) the other night and frankly the signal there was good but we couldn't do anything on our facebook, we tired uploading pic's and they would fail, tried severl time and same thing. So I decided to uninstall all the updates I had for facebook and go back to the stock app. Well that didn't work either so we gave up. The next morning before leaving for work I reinstalled the Facebook updates and went on to work.
Later that day (lunch) I texted my wife a few time and HEY!!! I noticed they were coming in order like they should. The only explaination I see is I remember a few facebook updates ago there apeared two new icons in my app folder, one was Facebook Messenger and I don't remember the other one and later after another update they were gone.....
Anyway long story short (sorry) I think when that happen it kind of messed up my stock message app, for what ever reason it's working great now and that's the only thing I did to my phone that was different.
Not sure if this will solve your problem but it's worth a try, uninstall all the Facebook updates and then restart the phone and see it you problem goes away. You can always reinstall the Facebook updates....