You could “solve” this problem by always turning Picasa off when you want to snap screenshots or map your favorite screenshot application’s hot key to another key besides “print screen” but both of those solutions are hardly ideal.
There’s two good reasons for disabling Picasa’s odd screenshot taking habits. One is just plain practical and the other is a matter of privacy.
2. Return to the Picasa folder and right click on the “Screen Captures” folder. Select “Properties” from the right-click context menu. Within the Properties menu, select the “Security” tab, as seen in the screenshot below.