The original "Flip Video For PC" software that came preinstalled on my Flip worked fine. But after being nagged to "upgrade" to FlipShare, I experienced the same crash problem mentioned here. Even worse, the FlipShare installation nuked the original program files from the Flip!
In my case, I think my computer's processor did not meet the minimum system requirements of the newer FlipShare software. The original "Flip Video For PC" software requires a 2Ghz P4 or higher; the FlipShare software says it requires a dual-core 4Ghz or higher. So when the FlipShare software tries to load the ippvideodecoder.ax module on an under-powered processor, it just crashes. Bad design.
I bet that most of the people posting this same problem here have processors that are "borderline".
Anyway, here's how to get the original Flip Video software back and re-install it on your computer:
Disclaimer: I assume no responsibility if you screw up your Flip or lose your videos. I can only tell you this method worked for me.
1) Use Control Panel, Add/Remove Programs to uninstall FlipShare and 3vix.
Important: this guy tells you how to back up any existing videos on your Flip BEFORE you format it.
After formatting, I had some initial trouble with the installation not finding my (empty) Flip. Here's a workaround: the installation creates a folder called "FlipVideo Updater Support Files", and within that a subfolder called "files_to_install". Copy the entire contents of that subfolder to the root of your Flip. Re-run the installation and it should now be recognized.
4) Bonus: once you've got the old software reinstalled and working, you may want to disable the annoying "Upgrade To FlipShare" nag screen that bugs you every time you run the software. Simply browse your Flip and delete the following file: