Uncaught SyntaxError: Unexpected token ILLEGAL

when the menu is not working (99% of the time) and the console contains javascript errors I noticed:
quotes does not work
customers works
invoices not work
products works
payments works
reports works

and the javascript console always shows:

Uncaught SyntaxError: Unexpected token ILLEGAL ("page"): 44

[where index page could be, invoice, quotes …]

OT: Happy Easter :innocent: