Volume keys doing strange things.

Please forgive me I am not computer literate. I will describe the problem as best as I can. When I try to use the volume up or down keys they do not control the volume but they make the screen change. Volume down makes the screen disappear or reappear and volume up bring up a calculator and a clock etc. Also there is a black box that appears every time I click on something. Any ideas what is wrong? Thanks for your help!

Bit hard to tell,

You may have enabled parts of Universal Access check your System Preferences.

Thanks for the reply. I 'm not sure what I'm looking for but I checked the settings and they look okay to me.

Maybe its Expose and Dashboard, check their Keyboard Shortcuts in their System Preference

Thanks very much Kaveman. I'm not sure what I did but I changed a few things and I'm back to normal.