I found in my experience, that may very well be your problem -- autosaves. Try disabling them. My game doesn't crash anywhere near as much as it used to after disabling this. Fortunately for me, I prefer saving manually anyway.
Fair enough. I've tried a few different things, but autosave doesn't seem to make much difference for me. Letting the computer sit and the screensaver go on almost always kills the game. I have a dual monitor setup with different resolutions on each (don't ask). Disabling the second monitor does tend to help a bit, so I typically do that and run at 1920x1080. Someone else mentioned anti-aliasing somewhere: I do have that disabled.
Processor: i7-2600K CPU @3.40 GHz (4cores, 8 threads). I forget what MB I have, but I think it's an Intel one.
Memory: 6GB
OS: Win8 64-bit
Gfx: Nvidia GeForce GTX 560
Hard Drive: 500GB SSD + 1TB data drive
Virus scanner: McAfee
I'm running on steam, and I have had some flakiness on steam games in general, but FE: LH is definitely my least stable game. With games like The Witcher I can do things like alt-tab around while loading and get fun effects like having no mouse pointer. Also, games like X-Com crash occasionally, but that's once every several days of playing, not several times a day. I don't think my general system stability is the dominating factor here.
If I had to guess it would be Gfx driver, 64-bit win8 flakiness, or multi-threading issues, but I really don't have any deep insight.