Mouse left-button makes a screenshot? Why?
 

After installing Nvidia Drivers and enabling desktop effects, my mouse just went crazy. The left button does a screenshot, the right button seems to do it's job. But when i press Shift+left button it does what it is supposed to do. I read around the Net and it turns out it is not so uncommon problem but still i couldn't find a logical solution. I tried the one with the Beryl Settings Manager but it didn't work. I would be really really thankful if somebody can give me a link to a site where i can find a detailed step-by-step solution or to tell me how to fix this.

In the Kde environment, you can define keyboard shortcuts to be whatever you want them to be. Go the Control Center - Regional and Accessibility - Keyboard Shortcuts to see what is set up by default, and to set your own shortcuts.

Gnome probably has something similar.

I confess that I am hard pressed to understand why your keyboard shorcuts would change after installing a graphics driver.