Why does the system freeze when using the program cat on large files? (I'm combining split vobs into one file after extracting with dvdfab through wine since I have a protected disc I own).

Is there anyway to prevent this? I have 6 gigs of RAM, a core i7, an otherwise good motherboard that doesn't show any problems and a system that is generally stable. Yet, if I try to do this I get nothing special in dmesg showing a hard drive problem, but I get a huge stall. The system does unfreeze if I wait but it is incredibly annoying not to be able to use a 4 core system with HT for a full 8 threads just because I want to concatenate some VOB files.

This doesn't happen throughout the whole process, sometimes it only happens if I'm trying to do other processing that's a little intensive, but the CPU is never maxed out or anything that I can tell so I don't know why the system does this since it doesn't show any indicators that I know about.