I had the blank page problem in the spring with my #1 blog. It was resolved by chmodding the folder permissions manually. Cause of the problem wasn't verified. Today this happened with other two blogs and the cause is verified to be W3TC 0.9.2.3:
1. Installed it to a newly-installed blog. All pages give now the error message "403 Forbidden
You don't have permission to access / on this server." The whole site is inaccessible after installing W3TC 0.9.2.3.
2. On another blog that has had W3TC for a while resulting in 90 / 100 in Google PageSpeed, I installed BulletProof Security .46.3. After letting it create secure .htaccess files, W3TC warned it needs to be redeployed. After clicking "Redeploy", all pages under wp-admin give "403 Forbidden
You don't have permission to access /wp-admin/ on this server." The admin pages are inaccessible after redeploying W3TC 0.9.2.3.
All three blogs are running on Apache 2.2. Both blogs that got problems today were WP 3.1.3.
Timlock, kayvic01 and noanylove: Is the the exact same problem you had?
W3TC Developer(s): Is this a known issue to you? Is there some additional information I could provide to help in solving the issue?
Everyone: You all know that caching is important, but admin panel downtime and especially whole blog downtime is absolutely to be avoided. Those downtimes have happened three times for me with W3TC. Can you suggest other cache plugins that don't have the same risks as W3TC? What about Hyper Cache + DB Cache Reloaded Fix?
http://www.tutorial9.net/tutorials/web-tutorials/wordpress-caching-whats-the-best-caching-plugin/#comment-40553 is the earliest comment I've seen, stating that the has problem existed at least since Jan 24.