Might want to check this article from Info Security magazine (you can get a free subscription if you're in North America). It was interesting to look at the Report Card and the Comparison of the AV vendors found on the left. TrendMicro seems to have some serious diagnostic issues.

There seems to be issues with troubleshooting and perhaps they -- and other software manufacturers -- have to go back to the basics of troubleshooting processes along with good customer service.