I am looking for any explanation as to why an Excel spreedsheet with 39 sheets and an individual protection password set for each would all of a sudden refuse to take the password.

This document needs to be updated with info from both my end and a vendor's end. Vendor kept messing up my formulas when updating her part, so I decided to protect each sheet (so that if I screwed up a password or two, it would not be a big deal to redo it). I used the same password for all sheets, tested it in a few, then sent it to her. I got it back by month end with her info, and when I tried to unprotect the first sheet to update my info, it would not accept the password. I tried with the second sheet, third, fourth, thing is, the password would not work on any of the sheets.

I really needed the file and had no time to do it all from scratch, so I had to purchase one of those password cracker programs to get my file back. So my problem was solved, but since I will have to protect the file again before sending it and I have another file that I have protected as well, I would like to know what could have caused this to happen. Was it something that I did, that the vendor could have done, or does that just happen every now and then as a glitch and I was just a lucky winner?

Any feedback would be greatly appreciated. To further clarify, the password that I used was nothing fancy. All small caps, no numbers, only five characters.