My MacBook Pro 13" had been giving me small but recurrent problems lately. Every couple of days for the past two weeks the spinning beach ball had been showing up and the Mac ended up asking me to hold down the power button to turn it off and then restart the laptop.
I checked and repaired the HD via disk utilities. It said it was repaired but it didn't make any difference.
Yesterday the beach ball appeares much more often (every half an hour, or less) so I decided to start in Recovery mode (cmd - r) and then just fully recover the system from the external HD I use with time machine.

That's when it went even worse. The recovery from the back up failed saying I should try again but when I try to start the MacBook only does two things: one - if I don't hold anything down it gives me an error and makes me force shut down the computer, which gives me the idea that everything is erased from the hard drive. And two - if I try to press again cmd - r, first the apple logo shows up and then it changes into the prohibited sign. It keeps thinking for longer than 5 minutes.
I don't know what to do anymore.

Is there another way to try to recover my time machine backup from the external HD?
What kind of problem could be causing all of this?

I have to add that as I'm traveling and away from home I don't have with me the system CDs that came with the MacBook.

Any ideas on how to try to restart and recover my MacBook?