Hi Oscar,
The alert you see is designed to contain all the information we (the support team) would need to troubleshoot the issue. It looks like you stopped transcribing it just before the most useful bit, so I can't be sure what your problem is.
The most frequent failure in this area is when people try to upload too many references in one go, we have seen succesfull uploads for a maximum of 5000 items in a single import, but a safe number will be between 2500-3000 items. I've checked the manual and we should add this inforation to it.
If this is not the case, another likely possibility is that you are using the wrong import filter. Starting from an EndNote library you can export your references in the RIS format, this makes the import trivial as RIS is the default import filter. If you are doing this already, and you see a nicely formatted preview in the "import new" window, then something totally unexpected is going on. I suspect it might be a single awkward and "offending" character that is not handled properly, if that's the case, I will need you to send us the RIS file (to eppisupport@ioe.ac.uk), otherwise you might want to take a screenshot of the error message (ALT+"print screen", and then paste the clipboard on a word file) and send it to us: this is usually sufficient to point us in the right direction.
I'm sorry you are experiencing this problem and I hope this helps,
Sergio