Microsoft Corp.’s Internet Explorer, Netscape Navigator and Netscape 5 Internet Explorer users have been hit with an unusual bug affecting some browsers.

Microsoft Corp. said Wednesday it has discovered a “bug” in Internet Explorer that prevents the use of some browser extensions and other Web services.

The issue affects users of Internet Explorer 5.0 and earlier versions, and may affect users of the Windows desktop version.

Microsoft said it was aware of the bug and will be working with the affected users.

The company’s Brian Beaulieu wrote on Twitter that the bug appears to affect Windows XP users.

Microsoft added that it is working with Microsoft to investigate the issue and said it is investigating what caused it.

The bug appears in Internet explorer 5.x.

Microsoft says that Internet Explorer 7 is affected.

Microsoft’s Internet Explorer team has posted a list of fixes on its blog that are expected to be available soon.

Microsoft and Mozilla have been battling for months over how to manage the open Web.

Mozilla has said it would block extensions in browsers that it says are not safe for its users.