I recently just upgraded to the latest version smarterstats (3.3.2950) as it stopped importing files, and that fixed the issue in the past. Now when it imports files, approx. 90% of the lines that are importing are bad lines so it there are 100,000 lines being imported, only 7,000 are valid and the rest are not working.
I am importing IIS W3C log files, and this has never been an issue before hand, and now it is a serious issue as clients reports are incorrect.