What Project Preset did you choose for your project? You might also find some helpful information here: PrE Hanging, or Crashing - Some Tips
Insanity is hereditary, you get it from your children
MOV is but a wrapper, and can contain a lot of different CODEC's, some not available for a PC. QT Pro has a pretty good Properties function (Ctrl+J), that should be able to tell you what CODEC is used. This ARTICLE will give you a bit more info.
So long as the CODEC used can be added to your computer, John T's suggestion to get QT Pro and use it as a converter is a good one.
What platform are you on? What is your OS?
I'm with Bill.
MOVs, like AVIs, can use any of hundreds of compression systems (codecs) to create their files. Many of these codecs are incompatible with Premiere Elements.
There's a good chance your ultrasound machine is using a codec that will not work in this program.
Using Quicktime Pro ($29 from Apple) to convert it to a DV-AVI will resolve the issue.