上海地区分布图:我的系统是XP,为什么老是自动返回到用户选择画面,我什么都没按

用注册表把系统优化一下吧，估计是你的机器上按什么软件或者你更改了哪些设置影响了系统的正常工作。
;禁用系统还原
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SystemRestore]
"DisableSR"=dword:00000001

;彻底关闭Dr Watson
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\AeDebug]
"Auto"="0"

;禁用错误报告但在发生严重错误时通知我
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\PCHealth\ErrorReporting]
"DoReport"=dword:00000000

;====启动和故障恢复====不自动重新启动\不将事件写入系统日志\不发送管理警报\不写入调试信息
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\CrashControl]
"AutoReboot"=dword:00000000
"LogEvent"=dword:00000000
"SendAlert"=dword:00000000
"CrashDumpEnabled"=dword:00000000

;从我的电脑中删除共享文档
[-HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\MyComputer\NameSpace\DelegateFolders\{59031a47-3f72-44a7-89c5-5595fe6b30ee}]

;不使用简单文件共享
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa]
"forceguest"=dword:00000000

;通过删除共享的计划任务加速网络邻居的浏览
[-HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\RemoteComputer\NameSpace\{D6277990-4C6A-11CF-8D87-00AA0060F5BF}]

;删除自动搜索网上邻居的打印机
[-HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\RemoteComputer\NameSpace\{2227A280-3AEA-1069-A2DE-08002B30309D}]

;屏蔽病毒软件监控
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center]
"AntiVirusOverride"=dword:00000001

;禁用(1)；有可用下载时通知我但不要自动下载(2)
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\WindowsUpdate\Auto Update]
"AUOptions"=dword:00000001

;不加载多余的DLL文件
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer]
"AlwaysUnloadDLL"=dword:00000001

;加快关机速度
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control]
"WaitToKillServiceTimeout"="3000"

;禁用Windows XP漫游 气球提醒
[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Applets\Tour]
"RunCount"=dword:00000000
[HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Applets\Tour]
"RunCount"=dword:00000000

;禁用IMAPI光盘刻录服务
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ImapiService]
"Start"=dword:00000004

;chdsk检查系统, 缩短等待时间为 3 秒
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager]
"AutoChkTimeOut"=dword:00000010

;登录画面时使用打开数字键
[HKEY_USERS\.DEFAULT\Control Panel\Keyboard]
;"InitialKeyboardIndicators"="2"

;登陆界面显示Administrator超级用户
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\SpecialAccounts\UserList]
"Administrator"=dword:00000000
"root"=dword:00000000

;开启大硬盘支持
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\atapi\Parameters]
"EnableBigLba"=dword:00000001

;缩短XP的开关机的等待时间
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control]
"WaitToKillServiceTimeout"="500"

;Disables Preview of Movie file formats (allowing you to move/rename/delete without errors)
[-HKEY_CLASSES_ROOT\.avi\ShellEx]
[-HKEY_CLASSES_ROOT\.mpg\ShellEx]
[-HKEY_CLASSES_ROOT\.mpe\ShellEx]
[-HKEY_CLASSES_ROOT\.mpeg\ShellEx]
[-HKEY_CLASSES_ROOT\.wmv\ShellEx]
[-HKEY_CLASSES_ROOT\.asf\ShellEx]

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\FileSystem]
;禁止创建短文件名。NTFS为了保持与MS-DOS和Windows 3.x的兼容,也支持8.3格式的文件名。
"NtfsDisable8dot3NameCreation"=dword:00000001
;禁止最近访问更新。在各个目录之间来回切换时，NTFS将更新最近访问的目录的日期/时间标签，在容量比较大的NTFS卷上，它会降低NTFS卷的性能
"NtfsDisableLastAccessUpdate"=dword:00000001
;"Win31FileSystem"=dword:00000000
;"Win95TruncatedExtensions"=dword:00000001
"DisableLastAccessUpdate"=dword:00000001

;disable ;; This setting allows extended characters to be used in 8.3 filenames. Short file names with extended characters may not be viewable on computers that do not have the same character code page.
"NtfsAllowExtendedCharacterIn8dot3Name"=dword:00000000

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion]
"Plus! ProductId"="Prepared By Zhufei"

;禁用杀毒软件提醒
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center]
"AntiVirusDisableNotify"=dword:00000001

;禁用防火墙提醒
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center]
"FirewallDisableNotify"=dword:00000001

;禁用自动更新提醒
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center]
"UpdatesDisableNotify"=dword:00000001

;忽略杀毒软件
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center]
"AntiVirusOverride"=dword:00000001

;忽略Windows防火墙
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center]
; "FirewallOverride"=dword:00000001

后台有间谍软件在运行，用点反间谍的软件搞搞就好了。网上有的是，我就不贴出来。见意到大点的网站下，并杀下毒，防止引狼入室。

在任务管理器里面注销一下就行