I must have been doing some pretty vanilla stuff as I've been using Vegas since Version 4 and have never had this problem.
Some months ago I purchased a DVD with a library of Video Background loops. I just tried to drag one of the AVI's to the Vegas timeline & it wound not drop. Just got a black circle with slash.
I'm assuming this is a Codec issue, but not sure. I'm seeing this problem on my laptop: Win 7 64bit; Vegas 9.0e 32bit. Here's the results of running Gspot:
Can anyone help?
...Jerry
EDIT: Here's another clue. I tried to open the clip in VirtualDub and got the following error: