I updated from Piwik 0.4.4 to 0.4.5, and I had this error for the "Last visits graph" widget:
OpenFlash Chart JSON Parse Error [Syntax Error] Error at character O, line 1: O:
See the attached screen shot. The bug occurred with a French interface. I chose English to know the translation of the buggy widget, and the bug disappeared in the English interface and also when I returned to the interface in French.
This is working on piwik.org.
Please send an email to hello (at) piwik.org (or PM 'vipsoft' on the forum) with login info and site URL.
Actually, as I wrote, it's working now, but I don't know if it's the language switch that fixed some buggy configuration.
Do you need view or admin access to the Piwik installation?
Sorry, I misunderstood. I thought the bug returned when you switched back to French.
Closing, as this is no longer reproduceable and we're already planning to change the chart loading in 0.5.