Hi,
There seems to be an shorcut key conflict in Eclipse. Try opening the XML with right click -> Open with -> System Editor in order to rule out the issue.
Shortcut Key bind setting can be done in Eclipse with Menu Window -> Preferences -> General -> Keys. I suggest you to restore to defaults and see if the issue persists. If so, then find the conflicting keys and unbind the command out of them.
BRs,
Lucas de Oliveira