No window borders in jaunty
 

Hi.. I installed compizconfig-settings-manager recently. When I enabled the Blur Windows effect, the screen went blank. I restarted the system, yet the screen used to go blank immediately after login. Somehow, I solved this problem by going to failsafe terminal and removing compiz-core. The problem was solved but now I'm not getting window borders at all. Alt+Tab isn't working either.

Try running
from a terminal, see if it helps---it should put compiz managing your windows again, if it isn't for some reason (obviously you need to have Compiz installed and working). If it doesn't help, you can try falling back to Metacity by using
Or if you use Emerald, you could run it's similar replace command to make it take control of your window borders. I haven't lost the borders often, but those times I have, this has worked.

Hope it helps :)