Users who thought the Windows XP operating system would be more reliable than its younger sibling Vista are being buffeted by reports that the latest update for XP, Service Pack 3, has its own problems.

A variety of complaints about SP3 are being posted on the Web, with users complaining about system crashes, spontaneous reboots, and other issues. On the Windows XP forum at Microsoft.com, for instance, a poster named Doug W. said that, after installing SP3, he had to use system restore “after three attempts, with different configurations each time.” He mentioned that his system has an Athlon chip from Advanced Micro Devices, and other users have reported similar problems with SP3 on AMD machines.