Changing the default duration only applies to new transitions in the timeline, not to ones already in the timeline.
Your best bet may be to delete these transitions and reapply them, if you have sufficient handles.
Lesson to be learned is to not use an unsupported OS with such a dated version. Had you stayed with XP, none of your current problems would have happened.
In general, it's always best to just use straight cuts with long enough handles when you are moving between OS, Platforms, Versions, etc.
Might be faster to simply remove all the transitions from the 6.5 project, open it in CS3 and re-lay the transitions, than to try to figure out what's happening.
Also, I don't know if it applies to your situation, but one thing I noticed in opening a 6.5 project in CS4 is that all of the fx Opacity settings get changed to Color instead of Normal. Click on a clip, open the Effects window and drop down Opacity to see if it's OK.
...Obviously Harm can type faster than me...
Thanks for helping me. I decided to reuse my old computer with XP instead, so everything works well, because i don't like the premiere pro nor the premiere cs3 versions, can't get used to them, so i'll stick with the old school stuff...
I've Imported several Pr 6.5 Projects into PrPro 2.0, and never had an issue. Now, some of these Projects (done by others) did have 3rd party Transitions and some that were probably just not available in PrPro 2.0*. PrPro was smart enough to flag each one, with the exact TimeCode, and let me know the name of each "missing" Transition. It was then a simple matter of going to each TimeCode, and replacing the missing Transition with one from either PrPro, or one of my 3rd party vendors. Did CS3 not give you these dialog screens? That would be a shame, as I found them very useful, and simplified the task of replacement to just a few seconds.
* most of these Projects were started on Pr 6.5 Mac, and I am on a PC, so I do not know which Transitions might have been on the Mac. A few were definitely 3rd party, if their name was any indication.
I never used Pr 6.5, only a bunch of its Projects, but find PrPro to be a wonderful layout. Back in the Pr 6.5 days, I was on Avid, an have never regretted moving to PrPro.
When you have some time, don't hesitate to give it another go. Just keep an "open mind," and let the work begin to flow.