two issues to be perfect

Since I use W3 TOTAL CACHE I sped up my blog, but I must solve two issues:
-sometimes when I access a page for the first time does not load the CSS file and I have to refresh the page. Then everything works.
– Google webmaster, about once a month, reports the following error:
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Possible outages 26 febbraio 2014
Dear owner or webmaster of •http://www.ilsentierodiarmenzano.it/cultura/
While crawling your site, we have noticed an increase in the number of transient soft 404 errors around 2014-02-26 21:00 UTC (London, Dublin, Edinburgh). Your site may have experienced outages. These issues may have been resolved. Here are some sample pages that resulted in soft 404 errors:
•http://www.ilsentierodiarmenzano.it/cultura/bergamini-a-san-rufino/
•http://www.ilsentierodiarmenzano.it/cultura/grotta-di-cinicchio/
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pages with errors are always different and if I perform the test they work fine!
Thanks for the help

https://wordpress.org/plugins/w3-total-cache/