OK. Give a read of this.....
Help running a 32 bit program on Windows 8 64 bit
3rd reply and read the link. Don't know if that's the problem of not.
There was also another post on this forum regarding w8 and DCU5 x64 not running.
W8 is different enough from w7 that weird stuff happens that I can't explain. I put W8 on the grandsons box and we've run into a few issues where items got corrupt without reason.
Roxio program gave me fits Until I wiped the registry in 2 locations. I'm interested in seeing how this turns out.
If you switch to DNG format, DCRaw will probably open the files, it's also free.
You might try contacting Ricoh support and see if they can solve the problem.