Updating Plugins – Having Difficulties

I am trying to go through and update my plugins. Each time I click ‘Version Details’, I’m taken to a page that says

‘An unexpected error occurred. Something may be wrong with www.ads-software.com or this server’s configuration. If you continue to have problems, please try the support forums.’

This isn’t consistant. Some plugins allow me to view the details, and others take me to the mysterious page.

Also, I need to manually update my plugins, so I would need to download the folder for the plugin and add it to my configuration. I’m unsure where these downloads are to be found