Custom Textures that don't retain original resolution

[Wyz]

I've been recently working on a new custom story, and I'm implementing an intro sequence of 3 backgrounds. The sequence works fine, fades in and out with no issues, but it's the actual textures that are giving me problems. They are 768x768, and are primitive backgrounds. In the HPL editor, they have perfect resolution, no blurriness. However, when I load up my game, they instantly become very blurry, yet still visible. The weird thing is, I'll load up the level in HPL after testing it and the textures' references are gone, and I have to have them point to the textures I made again. If it is any use, I used paint instead of photoshop to make the textures in the Materials editor, and used Alpha Blend and default object type. If anyone has an answer it'd be much appreciated!