Here's the crash report: http://puu.sh/5RPat.txt
@Th3F4114n0n3
That came to my mind, yes, because of the block disappearing. BUT, this never happened before 1.7; I'm still on the same server; additionally, if your theory was true, wouldn't the block stay removed? Immediately after I fall down, it comes back again, and stay there.
Thanks for your answers,
Reygok
Yep, I just wanted to report this, good thing I searched first! Basically, a right-hold-click does the exact same thing than a left-hold-click.