Quickbooks Pro v5.0 for Windows 

I've been told QuickBooks is a good product. I've only seen it from a cryptological point of view, and there was no product to look
at. Actually, there was nothing at all related to cryptography. 

Like Act! and many other modern business applications, the makers of QuickBooks (Intuit) decided not to bother encrypting
anything other than the password. For the password, they use a simple substitution chiper, which I haven't bother to figure out yet,
and probably won't. It doesn't matter much. 

In fact, all you really need to do is download a hex editor and head to offset 00001DD3. You'll see between 1 and 11 non-zero bytes,
one for each letter of the password. Set them all to '00' (hexadecimal) and your problem is solved.