problem with console unblanking and x

As far as I could understand, console blanking is enabled in /etc/rc with "setterm -blank 15" I have a problem with console unblanking. If X hasn't been started, console blanking and unblanking works just fine. If X has been started, and you have switched to the console, the console blanks (regardless you've been typing or not) after some minutes (I guess 15 but I'm not sure) and it doesn't unblank. Switching to X with alt+f7, exiting X and then trying to unblank the console typing something doesn't seem to work. Got any clue about why this happens? Thanks in advance. Best regards.