I have just resurected my piwik installation after a disc failure, and, apart from the missing data, it seemed to work fin again. I then upgraded to 0.5.4 (from 0.4.5) which I had to do manually in the end.
Notice: Undefined index: jsInvocationTag in E:\wampserver\www\piwik\tmp\templates_c%%F5^F50^F503D4A2%%graph.tpl.php on line 7
I have re installed manually just to make sure everything got copied but to no avail. Anybody got any pointers? Screenshot attached.