C.prototype is undefined

I am running 3.5.3

Using yslow, I get notified of these errors

mootools-for-dropdown.js

C.prototype is undefined
[Break on this error] var E=J.initialize;var B=J.protect;var...prototype;}C.prototype.construct or=C;

UvumiDropdown-compressed.js

mootoo...down.js (line 4)
this.setOptions is not a function
[Break on this error] var UvumiDropdown=new Class({Implement...}else{g[0]={opacity:0};c.start(g)}}});

Any idea on how to fix these issues or should I even be concerned?

Bob