[Plugin: W3 Total Cache] Settings Do Not Save

I have been using W3 Total Cache for about a year now, and it has been amazing. However, last week, my website started experiencing serious database connection issues as a result of the plugin. So, I had to delete the plugin and reinstall it. Now that I have reinstalled, the website is working properly again. Unfortunately, I am no longer able to modify the settings for W3 Total Cache. When I go to the settings pages (any of them), make changes, and click “Save All Changes”, the page reloads with all settings reverted back to their original state. On the Page Cache page, I also get the following error: “Unable to purge post”. Any thoughts on why I can no longer change the settings? Thanks!