Maybe running QuarterBackTools might be an idea?
I'm not sure if it will work above the 4GB limit (ASK SOMEONE before using it ;-) ) but if your partition is having checksum errors part of the QBTools program can check for bad blocks, this in turn will rewrite the volume bitmap which in turn will make your hd valid.
I can't check QBTools on my setup as I'm using SFS (I have a spare partition set aside for testing but it's gradually became full with me just dumping stuff looking for space ;-) ).