I found the problem, it is not construct 2 related.
I did not report a bug because I did not expect it to be. (you tend not to break stuff on new releases )
I went as far as installing r169 followed up by r168.
Both with the same result.
I think it might have something to do with my current video drivers.
After I installed r170, I also hit the update video card drivers ... and this is an old computer.
I think that broke something in my drivers, and now the export tool I use to create sprite sheets(fragmotion) gives me flawed sheets.
They appear to be Ok in an image editor (par some distortion on 1 or 2 images occasionally) but when imported to construct 2, they give me blank empty frames.
I tried importing images I exported last week, and voila, they worked without a hitch.
in short....time for new hardware -,-