Welcome to the forum.
First things that I would do is go to the mfgr's. Web sites for you audio and video card/chip and then download and install the latest drivers. Do not trust Windows to tell you if you have the latest - check this for yourself.
Then check for an update for Apple QuickTime Player. What version do you have installed?
For the CODEC issue, it could well be that your new OS is lacking some of those on the previous, though that would not explain the JPEG, for instance.
Going back, Windows would automatically install many CODEC's, including all the MS CODEC's. With some versions of Vista, one had to manually download and install a Vista CODEC pack. Now, I have a strong aversion to downloading any non-MS CODEC "packs," and would urge you to think long and hard before doing such.
If you do not have G-Spot, a great, free utility, I'd get it, and see which CODEC's are installed.
PS - for any error messages that you get with any of the Adobe CODEC's, see this ARTICLE.
Thanks for the input. Yes, I have the latest Quicktime Player (7.6.9) and all of my video and sound card drivers have been updated.
I will check on the other CODEC updates you mentioned...
I downloaded and ran the g-spot utility. There are none in the list that are flagged as "problem". I don't exactly know what to look for as far as what is the latest and greatest CODEC for each file type...This is a HUGE list...
OK, we just ruled out some of the more common potential problems.
Not sure if things are exactly the same in the newest G-Spot, but in my slightly older version, one monitors their CODEC's from Tables in the Toolbar. G-Spot will survey all CODEC's installed on the system. Remember, per that article, G-Spot, and most other CODEC utilities will likely report that a bunch of Adobe CODEC's are broken - that is because Adobe "hides" those.
That would still not explain the JPEG, as its decoder is built into PrE, IIRC. Also MPEG-2 is handled by an Adobe-installed CODEC from MainConcept. Something is just not making sense to me, but I can only just sit here, thinking aloud.
I believe that you mentioned that you did a reinstall of PrE. Did everything go well? Any error messages?
Good luck, and if you do find the issue, please, please update the thread, as I'm pulling my hair out here.
Yes, the re-install itself went fine (no error messages), but I still had the same issues after the re-install. I deactivated both Photoshop and Premiere Elements prior to removing and re-installing. This definitely appears to be an uncommon issue...