It seems like caching issue. Please try following:
– clear cache in Total Cache plugin
– if that doesn’t help try to disable all plugins (especially Total Cache) – disable one by one to discover if external plugin causes this
– last step if that you try to remove plugin and re-install it
It’s problem with WP Viral Payments, they are forcing z-index of all dialogs to 2 (very bad practice). I see it’s a premium plugin so please get in touch with author and ask them to fix this issue because this will mess up any other plugin that uses dialogs.