Windows adds .dat to all my saved files?

I bought a Asus ROG with W8 pre installed. I was making a logo with pixlr and saving it to my desktop when I noticed the only save option was "data file". So I saved it. I cant open it or naturally upload it to my website like I could with seven. Why is it saving with the additional suffix .dat example - logo.png.dat or logo.jpg.dat?
Saving it to my desktop and trying to open it suggests I look for apps to open it...really!:shock:

Thanks

Check the pixlr settings. Seems like this would be controlled there.