Issue with editing plugins

Hi there,

I’m having an issue when saving the settings for several plugins. For example, when I try to create a site map for the first time with XML-Google-Sitemap it just logs me out of the WordPress admin (and displays the login screen).

Similarly, if I try to update Stock Quote Sidebar, it does the same. I should also add that once I’m at the login screen, and I try to relog in again, it does not accept my password. I have to open a new browser to relog into my account.

Anyone have a similar issue? Or able to help? It would be much appreciated.