Unable to select the specified database

[eluser]Unknown[/eluser]
A Database Error Occurred
Unable to select the specified database: databasename
Filename: core/Loader.php Line Number: 346

At first, it worked fine, but then stopped working for an unknown reason. After refresh page, it worked.

in some pc, it worked fine. in some pc , it stopped working with the same error.


mysql and web in one server.