Preview not working properly

Hi,

Since a few days preview doesn’t work properly anymore.

For instance: I select an area of an image, and I’m darkening that area with the Image > Adjustments menu.

Then I click on the preview button to see the difference between my adjustment and the original situation.

In the past I could toggle (preview/no preview) as many times as I liked. But now I can only click one time. I can use the preview button to see the original situation of the selected area, but when I’m clicking again (to return to the preview) the check mark appears, but I don’t see the adjustments anymore. They are applied however: when I’m clicking OK the darkened area is appearing. But I would like to see them before clicking on the OK button, so that I can test with darkening and lightening until the result is what I want.

What should I do to restore the original toggling possibility?

I have another problem with the rectangular selection tool. When I’m selecting an area, a rectangle appears on the image - so far, so good.

But after that the function of the rectangular selection tool automatically changes in the rectangular deselection tool (icon with a minus sign). When there is a rectangular selection on the screen, I cannot put an new rectangle on my image, as the rectangular selection tool can only deselect parts of the image I put first. To put a new rectangle, I have to click on the image with the free selection tool to remove the first rectangle, and only then I can put an new rectangle (but after that, the rectangular selection tool automatically changes in the rectangular deselection tool).

What should I do to restore the original function of the rectangular selection tool, with the possibiltiy to put a new rectangle immediately?

Thanks in advance.

Johan