Schneier, who has written some of the most important books on cryptography and security practice, told vnunet.com at the Infosec show that users will become inured to constant warning messages and will stop reading them after a while.
Vista has a host of warning boxes planned, including ones for unauthorised access, unsafe websites and malware alerts.
"These warning messages are a mistake. The users will not be able to interpret what the warnings mean and make an intelligent decision," said Schneier.
"After four, five, a dozen, a hundred warnings you stop reading them. The messages become an annoyance and you click on them so you can carry on and do your thing."
Education would help, he explained, but the vast majority of computer users are not computer people and just use PCs as a tool.
Instead Schneier called on operating system and application vendors to change tack and make their products easier to set up and run.
The security expert agreed that the forthcoming Windows Vista operating system will be more secure, but warned that hackers will find new ways to penetrate it.
However, he acknowledged that Microsoft had made great improvements in writing and checking code.
Steve Lamb, technical security advisor at Microsoft, said: "Ideally you want security to just work like turning on a car ignition.
"But there's also personal responsibility of the user for security, just as there is when they drive a car."
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