My iPhone 4 no longer plays some songs since iOS5 update, how can i get these songs playing again

Question

So ever since I installed iOS5 onto my iPhone 4, some of my music wont play (not all, but some), what will happen is, while on shuffle, my music will play a song normally, then get to a song that it for some reason cannot play and either
a) plays another song, without changing the information about the song, then when the second song is finished playing under the first song's name, it gets to the second song's actual information and stops playing and moves to option b
b) does not play the song, does not skip the song, but has the play icon in the corner next to the battery, but it doesn't show any time going by on the progress bar of the song, but drains my battery
when i shake my iPhone after this (i.e. activates the automatic shuffle) if it happens to land on a song it can play, it skips to the next song.
It is incredibly inconvienient, and i understand that a new operating systems do have bugs, but I would like to be able to fix it as soon as possible
thanks for the help

Answer 1

I found a solution recently, (and well, this is the only apple product I own, so i didn't think to post it) basically what you do is follows
when your iphone is plugged in and you have itunes open, go to the phone page, then to the music page, select sync with library, but then select certain playlists. After that select none of the playlists (removing the music from your phone) and sync, then sync again with the playlists you want selected, and voila! Takes an hour or 2, but you can do it in the background of whatever else you are doing.
Cheers