Windows Movie Maker messes with quality of video?

I was editting a Minecraft video (How steriotypical, right?) and I was adding in 3 videos into Windows Movie Maker to trim them down into short clips for a montage but I noticed that 2 of the 3 videos had to "Prepare" and so I waited for them "Prepare" while I cut up the video that didn't need to. This video was HD as I recorded it, a sharp video but when the other videos prepared, they were about 240p or 360p for some reason. I watched the videos on Windows Media Player and they were fine, HD, but for some reason WMM just messed them up. Does anyone know how I could fix this?

"Preparing" is converting for use in Movie Maker and shouldn't lower the resolution of the videos.

Convert the video clips to high quality WMV files before you import them into Movie Maker. There are plenty of good, free converters out there. I haven't used a converter lately and can't name those currently available. Use a Google Search and look for reviews.

For a solution to the "Movie Maker saved my movie but lowers the quality" problem, try increasing the bit rate of the movies you make with Movie Maker. It's very easy to do. You just have to create a Custom Setting for the videos based on their HD resolution (frame width and height) and bit rates.