The RIAAthe trade group for the music industryknows that students are among the main lawbreakers when it comes to music sharing, and it is cracking down. The University of Michigan has received more than 400 complaints so far this academic year, compared with just 93 in the whole of 2005-2006, the Michigan Daily reports. And Michigan's just No. 18 on the RIAA's list. Ohio and Purdue universities, No. 1 and No. 2, have received more than 1,000 complaints against individual students since last fall, the AP reports. The complaints just mean that the RIAA sends offending IP addresses to universities. Figuring out which students belong to which IP address is difficult in the age of wireless communication, a Purdue spokeswoman told the Exponent.