I've removed acronyms.conf because I didn't want all kinds of stuff to be highlighted in my Wiki (btw, is there a way to disable this)? After clearing the cache I noticed that DokuWiki doesn't output any content at all anymore. That means: Header and footer (title, search field, navigation, buttons) were all there, just no actual page content. First I thought I had somehow messed up file permissions; but .xhtml cache files were written, each of them having a size of zero bytes.
It took me some hours to find my way backtracing from the cache access to the cache generation, then to the parsing, where I finally found out: in lexer.php, parse() returned false in line 404 ($currentLength == $length is true). Dumping the current parser mode told me it was _acronyms, and that's what rang the bell. I can't provide a patch because I don't quite understand how the parser works. confToHash() is alright, it returns an empty array if the file is not there. That's also why simply "touch"ing the file doesn't help either: There has to be at least one entry in the array for the parsing to work.
If you have any further questions, I'd be happy to provide you with more information. (Oh, and please, take care of #698 *g*...)