I have never seen that icon, so can only speculate.
As VOB's contain the MPEG-2 AV files, and they are often spanning several VOB's (each VOB can only be ~ 1GB, so longer MPEG-2's will span across two, or more), it might be that the MPEG-2 inside those VOB's does span several.
When you switch to Timeline View Mode, do you notice anything different, with regards to those VOB's? Are those files (actually the MPEG's in the VOB's) movable, in Timeline View Mode?
I Imported a full DVD of VOB's, into a Project, but did not get that icon, in Scenline View Mode.
When you hover over that icon, do you get a Tooltip, explaining what it means?
Unfortunately, I never work in Sceneline View Mode, and seldom work with VOB's, so it might be simple to explain, but I cannot do so.
Good luck, and maybe someone else will recognize the icon, and can explain what it signifies, and also why you seem to be locked out of editing those particular Clips.
Thank you for that. I had looked through the Muvipix Guide to PrE 7, but did not see that icon. Now I understand why it did not appear in my tests, as even in Sceneline View Mode, I had dragged the VOB's to the Video 1 Track. Makes sense now.
I was close, in suggesting that the OP look at things in Timeline View Mode, as that would have revealed those VOB's on Video 2, or higher.
Greatly appreciated, and I learned something new about Sceneline View Mode, which I have almost never used.
Thanks guys. I can see/edit the tracks in timeline view... I find it strange, I've been doing this a long time and never had to switch out of sceneline view for the simple cutting and transitions I do. I'm guessing something is different because I have switched to Windows-8. I notice Adobe doesn't support 8 for the old PE7 and maybe this is why-it works but strange things happen.