Only thing I can see is the opening and ending tag mismatch ('<Item>' (start with capital 'I') & '</item>' (start with lowercase 'i')) in this line:
It should be like this (both capital):<Item>dlcpacks:\mpxmas_604490\</Item>
Or this (both lowercase):<item>dlcpacks:\mpxmas_604490\</item>
to avoid a parsing error.
I'm not sure what effect this would have in-game though?! Let's see...
Tested: I can confirm that this opening and ending tag mismatch does indeed stop your add-ons (some anyway, tested quickly) from working.
Fix: Just change the lowercase 'i' at the end of the line to a capital 'I' & your add-ons should start working again