I'm also getting repeated errors. The failed processes eventually disappear from the list, but I don't understand why the vast majority of my share requests show errors. I have had quicktime error -50 several times, and also one project that keeps getting stuck after 95%. It's only a couple of minutes long. The last part of the log shows this:
Which makes it look as if it thinks it has finished when actually it hasn't.
There have also been countless other errors.