Some Windows XP users are having trouble installing the operating system's first service pack of bug fixes and updated drivers, leading them to judge the cure as more damaging than the disease.

Although SP1 plugs a major hole in the operating system, the fix has been painful for a tiny but vocal few of the estimated one million users who have downloaded the update, which was posted on 9 September. For the vast majority, the download and installation has gone well, according to a Microsoft spokesperson, who calls the process "smoother than a lot of previous releases".

But internet support forums show that many people continue to have serious problems with the update. The chief complaint is that their PCs run like treacle after installing SP1. Running a close second are reports that PCs refuse to restart after installation or become highly unstable. Some systems continuously reboot. Other users complain that applications won't start or now crash repeatedly, including Microsoft's own programs.

Other reported troubles — including problems in switching user identities, failure to install, disappearing screen icons and loss of both broadband and dial-up connectivity — are causing some users to shun the service pack, at least for now.

"If it ain't broke, don't fix it" says one post on an internet discussion board. "Stay away from SP1" reads another.

But Microsoft representatives say the company has not seen an undue number of users reporting problems. And, in fact, for the vast majority of users, the update fixes many more bugs than it creates. It addresses hundreds of fixes, including all of the company's previous security patches for both the system itself and for Internet Explorer 6.0.

"Windows XP Service Pack 1.0 is a well-tested release that corrects hundreds of bugs, including security-related ones. We encourage customers to install it at the earliest opportunity to ensure that their systems are fully secure," reads a Microsoft statement on the company’s website.

Despite Microsoft's ongoing endorsement, some users say they will wait to see if Microsoft comes out with a second version of the update. On internet support boards, the most common suggestion about installing it is to first save a "restore point," a Win XP function that essentially takes a snapshot of the PC's drive and specifications. Then, users are advised, they should reformat the hard disk, reinstall Windows XP, and then install SP-1 — and, of course, install applications and restore data files.

That advice infuriates some users who say a service pack should not require that users completely reinstall their systems. Or as one wag quipped on one internet site: "MS = Mighty Shaky."