I see, but judging from the error message, you have a syntax error in the Widget class file, which shows as:
PHP Code:
if($module->php) eval($module->php);
As you see, this line evaluates the PHP code for a module in your widget, so the syntax error is in the module. Did you edit any modules in ACP? Or did you create a new module with PHP code? If so, it may explain why you get this error.