I have problem with viewing the photos attached to posts over here since some time back.
I don't know if it's just my computer or it is like this for everybody?...

Before, when I click on a photo, it would open in a separate browser window, properly sized (depending on the browser's window size).
Now, when I click on an image, an overlay image opens up. It is ok if the image resolution is not large, I can see it properly because the image is displayed in the full resolution.
When the image is large, it stretches so much that I see only 1/5th of it and I have to scroll in all directions to see it fully. If you have several images attached to the post, the Left-Right arrows appear, but now you have to scroll and click to get to the next photo... It is quite uncomfortable I gave up on some photos...
An example of large images:
http://figs4funforum.websitetoolbox.com/post/My-Paradise-Nursery-fig-trees-6193088

So, can I fix it on my PC or it is like this for everybody?...

Don't know what browser you are using. I use Firefox and when I click on those pics I get the same as you do BUT if right click on a pic and chose open in new tab, a new tab opens and it  works without the scroll arrow

Ah! The right click does the trick, thanks! I use Safari. No arrows but at least I can see the photos fully.

Greenfig yes something seems to have changed as my thumbnail pictures when clicked on always were ok in size and now there huge for some reason .

So now my thumbnail pics i try fix to make even smaller so when clicked on one can view them better.
I tested and there smaller but will make them even smaller .

Greenfig some thing has changed. The picture are to big, HUGE in fact hard to look at.

i agree as well.
having some problem using google chrome