desktop icons all in one corner
Hi. Seems like every so often, when I turn it on after a shutdown, all my desktop icons end up buried and barely visible in a corner, usually the bottom left. Any ideas why this would happen, or better yet, how can I keep it from happening? Have quite a few icons and dragging them out of the corner, one at a time, is terribly time consuming. Thanks in advance for your help.
iMac (21.5-inch Mid 2011), Mac OS X (10.7.5)