ive had this happen before (pc version, 1.01 fwiw) what this means is that theres an undead guy up the hill or somewhere that is caught on geography or bugged in combat with someone. you just gotta run around till the next cinematic triggers.
also, this game is damn near as bad as diablo 2, ALWAYS ALWAYS have health potions, if you can manage this, you can swoop through nightmare with some intelligent character design like its nothing.
and a further sidenote; if you patch to 1.02 on PC (im not sure what the console versions do for obvious reasons) magic is severely nerfed, and archers are fucking brutal. whatever you do, dont enter certain fights with certain people using longbows in 1.02 and dont count on chain forcefield to save your ass.