I use windows 7. These solutions didn't work for me. However, in Solution 1, when I tried checking "disable visual themes" instead of checking "disable desktop composition", that seemingly fixed the problem. The game starts now.

Yeah, they adressed it as a bug http://www.swtor.com/community/showthread.php?p=8934878#edit8934878

I wonder if there´s a diference in drop rates between Solo and Solo+ modes? I did some runs in Solo+ and got like 3 pets dropped by the 7th boss. While in Solo I did more or less the same amount of runs without any drops of pet, just blue armor