here's the issue.
When editing a text layer with the type tool, without pasting or anything, just entering the editing of the layer, Photoshop somehow pastes some cache'd text. Mind you - this isn't text that would have even been entered during the editing session.
Please take a look at the video of this bug in action.
So instead of editing, sometimes, the text layer just pastes whatever from the cache.
This exact thing also happens, if you convert the group holding the layers to a Smart Object.
I can't figure out what happens that makes the layer affected or how to circumvent.
The only way I go around this is copying one of the layers that appear unaffected by this cache thing and editing them again, however, it does re-occur at some point after saving.
Please help, this is a really obnoxious bug.
I'm on Photoshop CS6 13.0.4 x64 on OSX 10.8.4 right now, but this has been happening to me consistently for about a year and I've been updating.
In fact I just updated to 13.0.5 x64 and still no cigar.