Lingering Problems After Uninstall

I think this plugin is awesome, and I think it’s just too awesome for my host. I tried it a few years ago on 1&1 hosting and had nothing but trouble. Tried it again last week on a multisite installation on my Hostdime VPS and couldn’t get it to work well yet again. I asked my host to change my PHP handler to work better with it, and they apparently changed it to “FCGID + APC.” Somehow, the combination of W3TC and the new PHP handler killed the site – the admin area was riddled with errors and the front end would give server errors or completely timeout.

I uninstalled W3TC, including deleting the cache folder and the other few folders/files related to the plugin (I think).

Fast forward to today and the site is behaving better. I think the new PHP handler is faster even if I can’t use W3TC. Now, however, my admin area is still generating random errors. The four I keep seeing are:

Fatal error: Call to undefined function postbox_classes() in /home/admin/public_html/wp-admin/includes/template.php on line 922

Fatal error: Call to undefined function is_plugin_active_for_network() in /home/admin/public_html/wp-content/themes/rt_omnicron_wp/functions.php on line 23

Fatal error: Call to undefined function add_menu_page() in /home/admin/public_html/wp-content/plugins/bwp-google-xml-sitemaps/includes/class-bwp-simple-gxs.php on line 353

Fatal error: Call to undefined function set_screen_options() in /home/admin/public_html/wp-admin/admin.php on line 75

Sometimes these error messages are the only thing that shows up and sometimes they show up in just one spot on the page (like the stats area of the dashboard, for instance). Whatever the case, usually simply refreshing the page solves the problem.

All that to ask: could this be a lingering W3TC issue?

http://wordpress.org/extend/plugins/w3-total-cache/