I reproduced the problem with arcade32.exe. It is a mame exception. I tried to extract the xml list from dos and it works, so I have to investigate why it's crashing in rc.
Meanwhile, get the arcade64 version which works correctly (?)
from a dos command as well. It is not romcenter related.
It doesn't happens each time. The xml file starts to grow, and stops before the end with an error. The file is incomplete and result to an 'invalid xml'.