I'm getting pretty much the same problem but I haven't looked at the rpt file. Yes I have a soundblaster 5.1.
I'm really getting both of your problems. I get regular ctd's (haha every 30mins - try every 5mins!). Up 'til now I suspected my motherboard so I'm about to install a new one so I'll see.
The other problem with being unable to save I suspect is something to do with the ecp. I'm unable to load a game saved while playing the ecp version using either ECP or plain OFPRes but if I just play normal OFPRes it's ok.
A real pain as I really like the ECP, which by the way, is the Dynamic Range Sound ECP.
I'll try lowering my RAM and AGP speed to see if that makes any difference as well but man, OFP is a buggy game. I'd give up if it wasn't one of my favourites.