Yes, there have been a few glitches. The new control system was done by a local design group and was not as reliable as it should have been. Universal identified the issues and has had them make the corrections. All in all, it is pretty stable now, but there are still a few things in the works.
As far as sponsors go, that's an expensive proposition. It's difficult for theme parks to get corporations to invest what is typically millions a year in attraction sponsorships. Today's companies have a hard time justifying the outlay on such things. AT&T and Universal actually started parting ways a while back.
There is a interesting story behind the ET rehab though. It was actually supposed to take place in 1999, but the rehab schedule had it closed for more days than was allowed in the contract with AT&T. The entire project was re-scheduled to fit and several of the planned tasks were done ahead of time. So, they did it last year, within the time limits, opened, and then AT&T didn't renew it's contract. Universal started using MCI long distance lines, told AT&T they couldn't put a cell tower on it's property, and switched all of it's corporate cell phone service over to Nextel.