可能有以下原因：
1.网络中断。解决办法：重新连接网络
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2.电脑中毒可能会导致QQ无法登陆。解决办法：使用360杀毒软件或其他杀毒软件进行杀毒
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3.电脑防火墙或杀毒软件限制了QQ的运行，导致无法登陆。解决办法：关闭电脑防火墙或杀毒软件
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4.QQ的版本过低。解决办法：定时更新QQ
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5.账号异常，例如QQ企鹅没事到处借钱。解决办法：关闭QQ企鹅
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拓展资料：
QQ是腾讯QQ的简称，是腾讯公司开发的一款基于Internet的即时通信（IM）软件。目前QQ已经覆盖MicrosoftWindows、OSX、Android、iOS、WindowsPhone等多种主流平台。其标志是一只戴着红色围巾的小企鹅。
腾讯QQ支持在线聊天、视频通话、点对点断点续传文件、共享文件、网络硬盘、自定义面板、QQ邮箱等多种功能，并可与多种通讯终端相连。
2017年1月5日，腾讯QQ和美的集团在深圳正式签署战略合作协议，双方将共同构建基于IP授权与物联云技术的深度合作，实现家电产品的连接、对话和远程控制。双方合作的第一步，是共同推出基于QQfamilyIP授权和腾讯物联云技术的多款智能家电产品。
工具：电脑版QQ。1、成功登录电脑的QQ后，点击界面左下角的“主菜单”，在弹出框里选择“升级”；
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2、就会弹出版本更新的提示框，点击下面的“更新到最新版本”；
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3、QQ软件更新文件就会开始下载，等待下载则可；
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4、更新文件下载完成后，就会弹出提示框，下次启动QQ后安装生效，你也可以选择下面的立即重启，重启后更新就会生效了。
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工具：电脑版QQ。1、成功登录电脑的QQ后，点击界面左下角的“主菜单”，在弹出框里选择“升级”；
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2、就会弹出版本更新的提示框，点击下面的“更新到最新版本”；
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3、QQ软件更新文件就会开始下载，等待下载则可；
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4、更新文件下载完成后，就会弹出提示框，下次启动QQ后安装生效，你也可以选择下面的立即重启，重启后更新就会生效了。
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