Hmm, 'ave ye downloaded any mods recently f'er the game? Mods like new skies, interfaces (buttons on the bottom right corner of the game screen), animation, and character models can affect how the game plays. If the files are placed incorrectly, this could result in the game crashing.
Also, 'ave ye tried running as administrator? Ye can do so by right clicking the FH icon and selecting the option from the list of commands that appear.