Adobe Photoshop Elements 8 stopped working - says serial numbers are not valid.

I have had Adobe Photoshop Elements 8 for several years and use it daily.  All of a sudden today, it would not open and showed me the screen to try the 30 free trial or to enter my serial number.  I entered my serial number and it gives me a red X and then tells me that my serial number is not valid.  I contacted customer support and he asked for my serial number and then told me he can't help with this issue and I need to look in these forums for a solution.  Anyone have any ideas??  I'm wondering if I uninstall it and re-install it, if it will accept the serial number then, but I'm thinking I'll lose all the preferences I have set up and have to go through and tag all my pictures again - and I have thousands.  Please help!!  It would be nice if the company could help.  :-(