Hi all, recently any images that I render and save are full of jpg artifacts even if they are pngs or tifs.   I can render at very high quality settings and I get a lovely, crisp render on screen.  I then save it as a png or jpg.   I can open it in PSP or PS and it looks fine.  I rework the image or crop it and it looks good.  I then save it.  If I send it to a friend or post it online it is terrible....full of artifacts and blocky.  As an extra note, I can create a vector image in XaraXtreme and save as a PNG and I get the same bad results.  I made some pngs for Poser yesterday and they are awful when I open the program.

 Here's what I've tried:

Jpg as progressive with no compression and Lossless.

PNG no interlace

Saving in PhotoShop, PaintShopPro and IrfanView.  Makes no difference.

Only thing that is passable (sp) is to render twice the size and manually downsize it small step by small step.  This is not ideal as rendering so large takes forever at high quality settings. 

Is it possible that my video card is dying?  Would this create this kind of issue?