Just curious if this is happening to anyone else still. I know its an old issue, but I would hope it would be fixed by now. Seems like after I play for a bit, and get in a couple intense gun fights, it just grey's or blacks out. The game has still been remotely playable compared to when it was released. But it still gets laggy and you get the odd freeze at some points.

Patch 1.07 is responsible for that. Sony's engine just isn't compatible with the codings, it seems. I've been experiencing extreme lags and freezings while doing the quest G.I. Blues and I repeated the same action twice over 2-3 hours while restarting an new game and all. I didn't notice anything about DT disappearing, though.

This happens when you use Med-X or Slasher. While under the influence of the drug, your display will flash from DT to DR. They fade in and out, with a black spot in between. When your Med-X wears off, your Pip Boy will display the DT pending the last display of the cycle. That's why it is gray sometimes and completely black, in others. On the 360 at least, a save/reload will reset it to the normal display.

The same thing happens when you unequip the Rebreather. Just equip it and unequip it , when the display is on the DT.

Ok, good to know on the med x, which I tend to use when its a big gun fight. I just need to figure out if I take more damage when it is grey/blacked out. Got a feeling you do take more damage that way.

I would say no. The flashing just shows you it's active with the DT. When you have a constant grayed or blacked out display, it just means the DR effect is inactive. You will still maintain your DT as normal.