When Windows Vista ships next year, customers might have a tougher time getting their security software to work properly, executives from Symantec said Wednesday.

At issue are two new features being introduced with Vista: an enhanced Windows Security Center as well as a feature in the 64-bit version of Vista called PatchGuard. Microsoft says it is adding these features to lock down the operating system, but Symantec believes that they will be harmful to customers by making it harder for them to use third-party software.

"There's no question that they're leveraging a monopolistic position to limit customer choice," said Chris Paden a Symantec spokesman.

While Symantec executives did accuse Microsoft of being more difficult to work with on Vista than with previous operating system introductions, they stopped short of accusing Microsoft of antitrust violations. "It's not anticompetitive behavior, because Vista hasn't even hit the market yet, " Paden said.

Security vendors like Symantec are in a state of heightened sensitivity these days as they've begun to compete with Microsoft head-on, and the specter of further antitrust actions looms over Microsoft's every move in the security space. Last week the European Union's spokesman on competition, Jonathan Todd, warned that the market could be threatened if Microsoft doesn't allow security vendors a fair chance of competing.

Symantec and other security vendors dislike PatchGuard because it prevents them from accessing the Windows kernel. They say it will stop them from delivering important features like Symantec's "anti-tampering" technology, which prevents malicious programs from modifying Symantec's own software.

PatchGuard will also make it more difficult for security vendors to protect against malicious software that takes advantage of kernel-level bugs, said Eric Sites, vice president of research and development with Sunbelt Software.

"There are a lot of new exploits coming out that exploit kernel-level drivers, " he said. "If we're able to get into the kernel, we can watch for things like that, but with what Microsoft is doing we can't do that."

Microsoft declined to be interviewed for this article, but in an interview with IDG News last week a Microsoft executive said that PatchGuard was simply an effort to prevent the kernel from being misused.

The IDG News Service is a Network World affiliate.