Hi,
I apologize for my rather naive report, but I think I've found a bug which prevents visualization of a rather unusual kind of AVI videos as exported from an (old) ultrasound machine.
This video format is contained in AVI files. The machine mentions RLE compression when saving. Apple Quicktime says the codec is "Apple - Microsoft Video 1, 532 x 432, Thousands". VLC shows "CRAM" in the codec info box.
When Perian.component is in the appropriate directory, playing the files in Quicktime results in a blank white window, with the application asking to search for suitable plugins over the Internet. Removing Perian.component from its directory solves the issue invariably. Not sure if it matters, but VLC is never able to reproduce these files correctly.