No problems at all other than it doesn't detect trojan horse attacks. For home use I have a PC, and got the Junkie virus from the internet. I put a Junkie-infected disk into a Mac and ran Disinfectant 3.5. Correct, except for macro and script based viruses in cross-platform products. Case in point, the recent Word macro virus.
Regular viruses are platform specific code.
However, a PC virus can infect a Mac running the DOS compatibility card or SoftWindows. After three years of using MacSchool our district is leaving it. The most problems originated at the high school. The primary problem here is that while Mac School will produce transcripts, their Guidance module that is supposed to produce credit worksheets doesn't work. In addition, GPA and class rank calculations were irratic.