We have moved on from 5.5.1 as we keep on having problems like Powercore crashes,Crashes in General,No VSTi 2.0 support and limited RAM use of 1.5 GB
http://www.logicuser.de/forumnet/vie...hp?f=18&t=5420 to name but a few.
We are now using Ableton Live which works great for us and you can get the job done in half the time and have 10 times more features.
In our opinion the best sequencer.
When we last used the Ti it worked OK with 5.5.1 but i think you might have issues with the new Ti Drivers.
I would move to Ableton Live but if you think its to much hassle to learn a new Sequencer then buy this Tutorial DVD and you will learn it in under a week
http://www.amazon.com/Ableton-Live-C...5837034&sr=8-1