PIWIK fails on showing results by months but if you apply the date range of the month it loads ok. What could be the problem?
Please check your php.ini configuration and web server logs. Make sure your memory_limit isn't set too low.
You could also try the qa build at http://qa.piwik.org:8080/nightly/ and then truncating your archive_numeric and archive_blob tables.
Please use the forum for further assistance. Thanks.