How to open the Finder ?

Question

Just installed Leopard on a 1.5 GHz Powerbook G4 with a 2 Gb memory, and the *Finder does not open*.
Neither can I open the Documents stack, or the blue boxes it contains ! I only get a message +"The Finder application cannot be launched -1712"+
However, my *data files* are *not lost* and can be accessed through the other applications.
Any idea how to solve this problem ?

Answer 1

OK, let's go straight to the answers by EricShapiro and Defrog. I edited them into the following procedure that worked on my computer. Before you start, get your computer login password ready to be typed;
1. Copy the following instruction (make sure you copied it entirely):
sudo mv "/Library/Application Support/DivXNetworks" "/Library/Application Support/DivXNetworks.prev"
2. Click on Spotlight (at the extreme top right of the screen : look for a magnifying lens)
3. Type the first letters of « terminal » until Spotlight finds the Terminal Application. Click on Terminal.app icon to open the application.
4. At the prompt, paste the instruction copied at step 1. Then press Return.
5. Type your computer login password. Press Return again.
6. Restart. You might have to hold the Power button down …to shut down and then restart.
It should work by now !