A study by anti-spyware software company Webroot found that spyware - broadly defined - resides in roughly nine out of ten online computers, including corporate and consumer PCs, eMarketer reports. Some 87 percent of corporate computers scanned had spyware, adware, tracking cookies, system monitors and Trojans. Excluding cookies, Webroot found a 55 percent; adware decreased on corporate computers, falling from 70 percent in Q1 2004 to 52 percent in Q1 2005. The average infected machine in an enterprise had 3.6 instances of adware, less that than the 6.9 average instances on consumer machines. Some 92 percent of consumer machines were found to be infected. Excluding cookies, the infection rate was 66 percent.