Sorry, I should have filled out more on the system when I posted my question.

I've got build 295 of Vegas Movie Studio HD Platinum 11.0. It loads into the (x86), so apparently it is 32 bit, though why it doesn't detect and install the 64 bit version I don't know.

The system is a few months old. Windows 7 64. I had a licensed copy of vegas 9 and 10, and had them working fine on here, upgraded to 11 and except for not importing the mov files from the Q3 that it used to, has been working fine.

I built and rendered several projects in version 10 using the MOV files from the Q3 with no problem. The Q3: http://www.zoom.co.jp/english/products/q3/

(well, did have an issue with trying to import 72 clips at once...)

I tried to used AVIDEMUX to change the container, but so far none of the files I've saved from there can be read by vegas studio. I suspect I'm doing something wrong with Avidemux, but the documentation is pretty sparse.

Quite likely Avidemux is only going to muddy the waters, unless it's capable of produce an edit-ready file.

What device is the MOV coming from? Is it a camcorder?

If you open the file in MediaInfo, what does it show for the codec, dimensions and frame rate?

Are you saying you're able to edit the file in version 9 and on the same computer -- but not version 11???

Just guessing but see if there's something for you
here
- or maybe an earlier version like 7.6.9?

The device is the Zoom Q3, known for excellent sound and only barely ok video, a trade off desired when sound is more important than the video.

Here's the media info:
Format : MPEG-4
Format profile : QuickTime
Codec ID : qt
File size : 135 MiB
Duration : 4mn 10s
Overall bit rate : 4 526 Kbps
Encoded date : UTC 2012-03-02 20:20:55
Tagged date : UTC 2012-03-02 20:20:55

Video
ID : 1
Format : MPEG-4 Visual
Format settings, BVOP : Yes
Format settings, QPel : No
Format settings, GMC : No warppoints
Format settings, Matrix : Default (H.263)
Codec ID : 20
Duration : 4mn 10s
Bit rate mode : Constant
Bit rate : 4 194 Kbps
Width : 640 pixels
Height : 480 pixels
Display aspect ratio : 4:3
Frame rate mode : Variable
Frame rate : 30.000 fps
Minimum frame rate : 29.412 fps
Maximum frame rate : 30.303 fps
Color space : YUV
Bit depth : 8 bits
Scan type : Progressive
Compression mode : Lossy
Bits/(Pixel*Frame) : 0.455
Stream size : 125 MiB (93%)
Language : English
Encoded date : UTC 2012-03-02 20:20:55
Tagged date : UTC 2012-03-02 20:20:55

Audio
ID : 2
Format : MPEG Audio
Format version : Version 1
Format profile : Layer 3
Mode : Joint stereo
Codec ID : .mp3
Duration : 4mn 10s
Source duration : 4mn 10s
Bit rate mode : Constant
Bit rate : 320 Kbps
Channel(s) : 2 channels
Sampling rate : 44.1 KHz
Compression mode : Lossy
Stream size : 9.55 MiB (7%)
Source stream size : 9.55 MiB
Language : English
Encoded date : UTC 2012-03-02 20:20:55
Tagged date : UTC 2012-03-02 20:20:55

See if this helps?
http://www.sonycreativesoftware.com/forums/ShowMessage.asp?ForumID=12&MessageID=803703
edit: seems that the OP found a solution there. Good.

Or this?

Try changing the setting. If that doesn't work, uninstall Quicktime, clean the registry (ccleaner or other) and then re-install Quicktime. See if that works. No guarantees, but worth a try.