Well, here it is my problem: W3TC won't save changed options.
At first I was trying to get it to save Memcache as the mechanism for Object Cache but it always reverted back to Disk. Then I deleted the plugin and re-installed it and now I can´t even enable any of the cache options but Page Cache. Database Cache, Object Cache... won't be enabled abut it also doesn't generate any error to tell the reason.
What could be causing these symptoms?
Thanks a lot,