First error: Each day started with over 50 visitors. Like 37 google organic, 7 google images, 8 bing… etc.
Steps to (unsuccessfully) solve it:
I removed all tmp folders. No change.
I deleted the entire Piwik folder and uploaded a fresh downloaded installation. No change.
I deleted entire Piwik folder and downgraded to latest 1.* version but then I lost all my history. The furthest day I could look back was a day before.
I removed all tmp folders again. No change.
I deleted the entire MySQL piwik database, the user and anything that had anything to do with Piwik. Also the Piwik folder on harddrive.
Fresh install of DB user, DB and Piwik folder.
Same error.
Updated to 2.0.1 and it got worse. Same error as before and after 6 hours Piwik stopped tracking almost entirely. Only the real time widgets work. Anything else stopped.
Yeah, looks like the “first error” is time zone related.
But the second error (which started with Piwik 2.0.1), which shows only live tracking but no regular tracking anymore, is not related to the time zone bug.