早上发现网站打不开，提示：
The 'System.Web.Security.SqlMembershipProvider' requires a database schema compatible with schema version '1'.  However, the current database schema is not compatible with this version.  You may need to either install a compatible schema with aspnet_regsql.exe (available in the framework installation directory), or upgrade the provider to a newer version.
因为我的网站一直都运行的好好的，所以只可能是aspnet_SchemaVersions这个表里的数据被破坏了，进去一查果然，表里被注入了一段JS代码，重启IIS，网站运行OK！
解决方法是在aspnet_SchemaVersions里输入如下数据：
Feature     CompatibleSchemaVersion    IsCurrentVersion
common                         1                          1
health  monitoring         1                             1
membership                 1                             1
personalization              1                         1
profile                             1                             1
role manager                 1                             1