Mac doesn't respond after sleep mode: how to Prevent this? My mac often doesn't respond after sleep mode. What can be the reason?

There are a lot of articles about what to do in this situation. But I can find nothing about how to Prevent it.

Mac is macbook Air. OS is OSx 10.7.4
I had the same issue on my mini.  The first thing you might try is resetting your PRAM and then your PMU.  These control sleep on your mac.  If they fix it, and it goes bad again, you may need to take it in for warranty repair (if under warranty.)