I'm working on a new MacPro 5,1 with 24 gigs of RAM running on OS 10.6.6
If you have each of the above Adobe Flash programs available, I found that problems may still emerge. Some of your files may have been brought into CS3 from older Flash programs, and some might be too large for the conversion processes to work on your system. I have a single Flash file over 65mgs, with abundant assets. Small files usually work fine, but larger ones often crash while opening them into CS4. With larger files I also often get a 'low memory' error message when opening them from CS4 into CS5. I have to use force quit to get out of CS5, and no amount of clicking will bring down the error window no will the program allow me to quit---a real glitch in the program.
NOTE: Adobe has made it clear that you cannot bring a CS3 file into CS5 directly. You must pass it through CS4. If you don't have CS4 then find someone who does, bring your files up in CS4 and save them in CS4. The take them back to your CS5 and if they are not too big they should come up in CS5.
Here is what I discovered about glitches in the above after many days of trial and error. I hope it will help if you have similar problems.
1. Solving a a possible CS3 problem---For what ever reason my many CS3 Flash files constantly would not open in CS4. I reinstalled CS3 (which I unwisely had deleted when I installed CS5) and went through the Adobe software updating process for CS3. I found that I could correct the problem by copying all of the key frames into a new CS3 file. Here's how.
a. in your main time line in CS3 select all the key frames by clicking the top left (holding down shift) and then bottom right (or visa versa). This should select every thing, turning this part of the timeline dark.
b. Without distrubing the time line selection, go to the little double boxes below the timeline (third little icon named 'Edit Multiple Frames' when you pass your mouse over it). Click this, and a litte area on the top of the timeline appears which allows you to extend it over the entire time line. This actually selects (and shows) every frame and asset in your file. NOTE: If you forget to extend the 'Edit Multiple Frames' over the entire area of key frames then you will not be copying all of them.
c. Without disturbing anything, hold down Control on your keyboard and click and hold. A menu will appear. Choose 'Copy Frames' and let go. Now you have all frames in the file on your clipboard (in memory).
d. You can now either close the file (Command W) or just create a new file which will appear in the tob tab. Do not quit Flash, but simply close the file if you have to due to memory limitations. In the new, empty file simply click once on the top left empty key frame (no need to name layer), hold down Control, click and choose 'Paste Frames.' The entire set of key frames, together with layer names, should appear. For larger files, wait long enough for the process to complete and the layers and their key frames to appear.
e. Save your new file with a new name. I usually put CS3 at the end of it to see what program it is in.
2. CS3 into CS4---With this new file I have had no problem bringing up the CS3 file in CS4. When I save I change the 'CS3' to 'CS4' in the file name to keep things straight.
3. CS4 into CS5---If the file you are working with is not too big (contains big assets or some big movie clip, etc.) then I find that it opens well in CS5. However, I have also found that my bigger files give me an error message after my cursor keeps spinning in CS5: 'Could not open one or more scenes probably because of low memory.' I have written Adobe Flash about this apparent CS5 memory problem which does not appear in CS3 or CS4 with the same files, but have received no reply from them nor on the forum.
To overcome this I have used the same frame copying/pasting frames method above (with the Control/click menu). I simply delete a heavy *layer* of assets and save the file by a distinctive name (to know later what I'm doing). I make another file with only the other layers. This usually allows me to bring both separate CS4 files into CS5. Once I have both in CS5 then I can usually bring up one, select the layers I want to copy again, by the method. above. NOTE: Remember not to use the usual cut/paste but rather the Control click menu. In order to copy the frames of one of these CS5 files into another I close the file (don't quite Flash!), bring up the other CS5 file and paste the layers in. Before I Paste Layers I create a new empty layer and put it where it belongs in my layers (or on the bottom and later move things around). Then I select that empty layer or the first key frame in that layer and again use the Control menu 'Paste Frames.' The layers should appear on and below with their names and contents. NOTE: The background size and color under the top menu Modify/Doccument does not transfer over, and thus you must reset this in the CS5 file.
There are other ways to do this, such as a verticle selection of key frames. Try to do this with a logical division of frames to keep things in order. If you keep your CS4 file intack (have a spare copy or use undos to get back to the originals) then you can keep trying until you get it right.