i've encountered this problem twice.....both after game crashes.if u are using a full install (recommended due to having no delays on loading sound)
(i had to) do a full reinstall....u can back up your savegames (not sure if this is just your savegames dir (someone help )
if u have opted for the normal install there is a walkaround....im afraid i cant remember it myself; however it was posted on the boards at www.heuristicpark.com some time ago
it is possible to use this walkaround for a full install as it redirects the game to read sound files from your cd (recreating the delays which is probs Y u went that route in1stplace)...hence it should possible for a full install too ie to redirect to your HD....
i think the heuristic boards are the place to go for bug problems....may help the advancement in future patches....plus there is more regular posting there....