Hard To Boot My Os At 1st. Intent

After solving a sound problem with the help of a really nice guy (oldcpu) as detailed here, now I'm having another headache.

It's getting hard to boot my system at 1st. try, it usually accomplish to boot normally and reach the login screen after 2 or 3 intents. I really would like to know if there is a way to know what's causing this strange behavior.

I guess that's something related always with the sound, since sometimes I get into the system, and log normally with my user. but the sound is a mess, it didn't attain to start well. The sound is intermitent, slow, buggy... well, it's a mess! But that's only sometimes, not always.

Other times, like happened today, I log with my user, and once staying already logged, the system just freezes. So can't do nothing! I have to perform a hard reboot.

Is there a way to consult a file that stays in the system about the earlier boots, containing the possible problem why the system, didn't boot normally the earlier time ??? That will be nice, so I'd be able to know (well, in fact, us, since I really doubt, I will understand the output, lol) what is making the system to get freeze sometimes.

Thanks for giving me any ideas, about how to solve this annoying issue.