Jane Maliouta, a Microsoft program manager, warned users in a post on the IE blog as the company delivered Release Candiate 1 (RC1) of IE8 today. It's a repeat of a similar caution she gave last August for IE8's second beta.
In the post, Maliouta recommended that users who had installed IE8 Beta 1 or Beta 2 before upgrading Windows XP to SP3, manually uninstall the older IE8 previews. Users who don't heed her advice will be stuck with both IE8 RC1 and Windows XP SP3.
"Windows XP SP3 and IE8 RC1 will become permanent. You will still be able to upgrade to later IE8 builds as they become available, but you won't be able to uninstall them."
A dialogue will also appear to warn users of the lock-in effect.
To avoid lock-in, Maliouta instructs users to first uninstall Windows XP SP3, then uninstall IE8 Beta 1 or Beta 2; then reinstall XP SP3 and then install IE8 RC1.
With IE8 RC1, Microsoft no longer asks users of Windows Vista and Windows Server 2008 to manually uninstall earlier IE previews before installing RC1. Because of the change, Microsoft will be able to push the RC1 update to all users running IE8 Beta 1 or Beta 2 via Windows Update at an unspecified time in the future.
Nor is there a timetable for delivering an update to users running Windows 7 beta, which has been public since January 10. Windows 7's version of IE8 is "pre-RC," and will eventually need to be upgraded.
An additional update is required before IE8 RC can be installed: without it, IE8 RC1 will balk during setup and show an error message saying "Setup cannot continue because one or more updates required to install Windows Internet Explorer 8 are not present." The patch is a revised version of a Vista SP1 prerequisite that sent machines into an endless round of reboots.