Try deleting all of the files in the '..\Divine Divinity\Run\Dynamic' folder.
Then start a new game and see if the problem persists. Save, then use iZakaroN's SaveEditor (or from Kiya's site, with description) to boost your stats (especially constitution), re-load and try running to Verdistis or the Dark Forest.
If the new game works, but the latest save does not, there may be a problem in the saved game folder itself. If neither work, it may be a problem with Divinity, in which case re-installing might help.
I have tried this method. Kaboom! The same thing even for a new game...
The next thing I'll try is re-installing. Heh, no one promised that the life would be easy... <img src="/ubbthreads/images/graemlins/ouch.gif" alt="" />
