Hot drinks and curdled protein powder

I don't microwave mine. I mix mine into a paste and slowly add boiling water while stirring. Smooth and lump free every time.

So I guess it's not so much the PP brand, then.
It does seem erratic, though, because I've made it exactly this way before, and it stayed smooth. But that time was a different brand (EAS) and a different microwave.
I'll try these tips. I've been really bad on my protein the last couple of weeks, I need all the help I can get.

I make a paste with the tap water as well.  I heat the rest of the drink extra hot and then use a little whisk as I add the hot liquid to the paste.  I never get lumps that way, but I have tried mxing stuff cold and then microwaving....and always got lumps.

It sounds like tempering eggs before adding them to something hot... so you can get something smooth and delectible rather than chunky.  One of my protein brands is clearly labeled that it will curdle over 120 or 130 degrees... so I was basing my comment on a manufacturer's information.  Mmmm... can't wait to have a *good* protein hot chocolate.  One of my protein powders is rather nasty when it's hot... it brings out the protein smell/taste, even with SF syrups added.  Time to try another one!