"Guest" @ 19.57 was me.
My FB problems began with Safari on OS X 10.4.11. Used Firefox successfully for a while.
Necessity for Skype led to upgrading from a G4 machine to a Macbook (2008 vintage) for which Safari on 10.6 brought back Facebook as before. A few months ago Facebook changed format, losing access to Comment and Share facilities (and copy/paste). Move to a different Macbook with 10.7.5 didn't initially solve the problem, but finding a suitable (but now unsupported) version of Firefox has brought Facebook back to a usable state.
Unfortunately Skype is no longer supported under any of these regimes, so I will have to see if I can upgrade to a more up-to-date OS X, possibly on a desktop machine.