We have a similar issue.  We are running on the next to latest version of Smarterstats, and for the past couple of months certain scheduled reports fail to send.  They keep retrying and eventually do make it through, but this takes days and repeated timeout errors.  It is only on reports for our larger website that gathers data for year to date and/or last year's data.

All the other reports, and these reports on smaller sites, work just fine.  These are custom reports on Keywords and Phrases as well as Visitor trends.

The error we get starts -