With reports whirling about how unprotected PCs can be hijacked within minutes of coming online, it would be no wonder if computer users have modified their behavior. A study conducted by Pew Internet & American Life Project (PIP) found that nearly 91 percent of those surveyed have done just that.

The report revealed that approximately 93 million Internet users in the U.S., or 68 percent, have experienced computer problems within the past year that are consistent with malware.

60 percent of that population did not understand what had caused their troubles with some 25 percent not knowing why new programs and desktop icons had appeared on their computer. 18 percent, meanwhile, had their Internet Explorer homepage forcibly changed.

PIP Associate Director Susannah Fox said that those with broadband connections were most vulnerable, especially if they engaged in risky activities. Fox said that some of these activities include swapping files on peer-to-peer (P2P) services, visiting adult Web sites and playing online games.

In consequence, a vast majority of users -- 81 percent -- have stopped opening e-mail attachments impulsively without knowing if they were safe; 48 percent put more consideration into what Web sites they visit; and 25 percent have stopped downloading music and videos from P2P services.

Others have made the switch to alternative browsers such as Mozilla Firefox to avoid having malware deposited on their machines. PIP estimates this sample to be 18 percent of the total population being surveyed.

"Familiarity breeds contempt when it comes to spyware. The more internet users know about these programs, the more they want to sound the alarm and take steps to protect themselves," said Fox.

"These survey results show that as internet users gain experience with spyware and adware, they are more likely to say they are changing their behavior. But what is more alarming is the larger universe of people who have struggled with mysterious computer problems, but have no idea why. Internet users are increasingly frustrated and frightened that they are not in charge of their internet experience."

Despite changing behavior, the report found that 73 percent of respondents consented to user agreements, granting adware the administrative permissions necessary to do anything that its developers had devised.

The upcoming Longhorn release of Windows strips user accounts of administrative rights to help foil the accidental installation of malware.

The survey was conducted over the telephone and the sample was comprised of 1,336 Internet users. Consistent definitions were used to describe malware. The full report may be viewed at the PIP Web site.