My previews with alt + tab

My alt + tab views keep giving the same error as the transparent gray square

meaning? clarify please

Is this the problem:

I did what this topic recomends, I’m just waiting of this error is if to be continued

I still dont know what youre talking about. Please post a screenshot

when happen the same error, I’ll take the print. But the error is the same of this topic I mencionnated, instead of showing the open windows, it shows that same square