My site fell from PR 5 to PR 3. I think of it i have paid links. Can banned me in Adsense for paid links on my site? thx! sorry for my bad english ;-)
There is no connection between paid links and AdSense. Google does not like any artificial traffic, that is what you should worry about. Just make sure you are not displaying pages with ads in any manual/auto/incentivized/etc exchanges.
Don't worry about links. It has nothing to do with adsense. Also you can always use widgetbucks or adbrite so you can be sure you are completly safe
A myth that Matt Cutts has confirmed and google has even announced it. Selling links doesn't affect anything you do in adsense