I have create a simple widget plugin, it's so simple and it make no changes in cookie setting, also it work great in my local site , but in the host i have a problem after activate this plugin and try to login the WordPress again, it says:
ERROR: Cookies are blocked or not supported by your browser.
or a whitepage show after logging in, and dashboard do not appear.
after deactivating the plugin every thing will work correctly!
what is the problem? is there any thing that i must add to my plugin for setting an special cookie?