“I have a Sony Handycam with a hard disk drive / Memory Stick Pro Duo. I can upload videos from either onto my computer and they will play. The problem I am having is that when I try to import them to Windows Movie Maker, I get this warning: 20090731112533.mpg could not be imported. An interface has too many methods to fire events from. How can i remedy this?”
Windows Movie Maker is notorious for only working well with DV-AVI camcorder files and WMV files. Any other file format that works was a stroke of good luck. Your best bet for editing the file would be to use some other software, but if that’s not an option here are a few suggestions for getting past the error message and on to editing your movie.

Convert .MPG to .WMV
If you want to use Windows Movie Maker to edit your Sony Handycam .MPG files, your best bet is to convert them to WMV before attempting to edit them. In most cases, you can download WinFF and convert your .MPG file by choosing Convert to Microsoft and Device Preset WMV2 Generic.

In some cases, WinFF can’t read the audio stream in camcorder .MPG files correctly and you may actually need to download a video converter that isn’t free, like Digital Media Converter Pro. If you reach the point of needing to purchase a file converter, you may be better served by purchasing video editing software that’s up to the task of editing your movie instead.
Editing Your Sony Handycam .MPG
A more ideal scenario than converting your file and editing it with Windows Movie Maker would be to use a more robust video editing solution. For DVD camcorders, I recommend either Roxio Creator or Sony Vegas Movie Studio because they both are designed to handle the types of video files created by hard disk camcorders. Since you are specifically using a Sony Handycam, in this instance, I’d give a nod to Sony’s software solution because they do put effort into making sure their video editing software works well with camcorders carrying the Sony brand name.