I had the same problem and it has a lot to do with how the mp3 was originally encoded. If you're getting files from various sources you will have various results. Sometimes it's just a matter of converting the id3 tag in iTunes to a later version like 2.3 or 2.4. Othertimes you have to use an mp3 tag converter like mp3 rage for mac or dr. tag for pc.

It seems like a lot of mp3's that were encoded a while ago are very difficult to convert in just itunes.

AM, I used to spin at Prey in LA using SSL... I know you spun there thursdays, right? If you're making the jump to SSL be very careful with the quality of your MP3's because a slightly corrupt file can mess up your whole set. I encode everything at 256 or 320. 128 just sounds like shit in a club. I know you scratch a lot so you might want to even have some uncompressed AIFF's to use for heavy scratching ( the reason for this is an AIFF frees up processer power so you can set your USB buffer to the best setting... i.e. less latency ).

Using the "convert to mp3" function in iTunes won't help much but the reason it's changing your 128k's into 192k's is most likely because your preferences in iTunes are set that way and 192 is the default I believe. You can change that setting to whatever you like but again, I don't recommend using any files that are 128.

i had that problem with a few songs and I found out they were checked for "ready only" in the file properties.... is that maybe the problem?

sorry... should say "read only"