That depends on what you used for LOD mods. If one of the _far.nif files was corrupt, it would manifest itself as you describe. Crashing trying to enter a world cell. Early versions of RAEVWD for example has this issue due to one of the Leyawiin meshes being corrupted.
As for my specs, I'll just copy my Nexus profile info:
Processor: AMD Phenom 9850 Quad core
Memory: 4GB Corsair Dominator
Motherboard: MSI KA92 Platinum
Graphics card: AMD Radeon HD4870 1GB
Sound card: Sound Blaster X-Fi
Monitor size: 19
question though - how does one reduce texture size?
Is that like a graphics rendering tool or something?
Try grabbing a copy of PAINT.NET. It's simple and quick and you can resize images and generate the needed mipmaps along with it. Just be sure when you do that you also use it to adjust the normal maps to match.