JoeGraham, as much as it's sweet to put me in your topic title, it's really not needed. As you can already see, there are more capable people who can respond to your query and the best it's likely to do is infuriate Ter and Graeme Kelly (the mods on this forum) and myself!
Anyway, the problem...
Before we start, consider checking to make sure that your FM version is 6.0.2 (the latest version), 6.0.0 is the version off the shelves. Then, follow these next steps.
Stevenhp1987 is right, and the first step should be to check the writable status of the db files.
If the problem still occurs (which generally happens), go to your My Documents folder and to location where your backup database is stored (My Documents\Sports Interactive\FM 2006 Data Editor\backup)
Copy the backup to the data\db directory which Steven has already mentioned.
Doing this WILL wipe any and all existing changes made to that db as it will be replaced by the backup which is a clean version.