I am receiving this same error with the exact same files as i am currently trying to install the same thing. After googling for i dont know how long anymore, and resisting the urge to post on here asking for help because i see how frusterated you get with people asking these questions. However reading the FAQ does not fix my issue. The files listed below are legitimate install files with what seems to be a proper xml file located inside.
cb_plug_pms_uddeim.zip
cb_plug_pms_uddeim_blocking.zip
cb_plug_pms_uddeim_inbox.zip
cb_plug_pms_uddeim_profilelink.zip
All of the other files uploaded and installed fine , but these 4 listed above gave me the same reported xml error. I am using joomla version 1.7 , please do not tell me to look at the faq because i have read that short bit of answer multiple times making sure that this is an error before i come post here. Any help is greatly appreciated in fixing this issue as i have been googling for hours, ive read atleast a half dozen posts on this site of ppl having the same issue but no fixes. Again, any help is greatly appreciate and thank you a ton in advance