Hey,
I've searched through the forums (and google), haven't seen anyone with a similar problem, if there was I apologize!
My version is 4.0 and it's on a dedicated server. I upgraded to 4.0 straight from 3.5 but the problems occurred even before the upgrade. I also use Cloudflare.
I have always been using WP Super Cache for caching and it was working like a charm. Suddenly it "broke", it kept telling me "timestamps don't match" for those familiar with the plugin and the error log said it had to do with the output buffer (ob_out). I have done extensive research, de-activated all plugins, erases occurrences of ob_out in the theme but nothing changed.
I then moved to w3 total cache out of frustration. Sometimes caching would work, others it wouldn't. From some point on, browser caching was not working at all. In addition, I would occasionally get spikes of cpu and memory overload on my server (load average would reach 60 some times!). The mysql process list, showed that w3 total cache and wordference were using most resources. I deleted both, the spikes seem to have stopped (i hope not temporarily) but I still have not resolved my caching problem!
So I went on and installed Quick Cache, which did not seem to work at all. I did not see any improvement on performance, nor the timestamp I am supposed to see when it's working.
Please note I have also thoroughly examined file permissions etc. So to my questions:
Has anyone seen anything similar before?? If so how did you resolve it??
Is there a chance this is a server issue rather than wordpress issue? IF so, what cause server configuration to change??
In general, If you have any idea or thought about this issue, please let me know!!
Thanks