Hey guys,
I am running Bitcoin-qt on Windows 7.
About a week ago I purchased around $1500 worth of Bitcoin and withdrew it into my freshly downloaded Bitcoin client. I decide to protect it with a passphrase, so I open up KeePass, a password database I use often and generate a secure password and encrypt my wallet with it. 5 Minutes later, I decided to change the passphrase with a more secure passphrase (not sure why), so I generate a 128 bit secure password, change the passphrase on my wallet file, and overwrite the passphrase saved in KeePass earlier. I save the KeePass database and to be extra safe, I back up the database to an external drive, as well as my wallet file.
Fast forward to yesterday. I had to restart my computer for some reason. Prior to this everything was working fine, and my passphrase from KeePass worked. Today is the first time I try sending coins since restarting my computer, I go to enter the passphrase saved in my KeePass database, and boom, it tells me I'm using an incorrect passphrase. You can imagine the feeling in the pit of my stomach. I tried restoring the backups and nothing works. I see no reason this should have happened since I saved the passphrase inside KeePass. I could see if I had forgot to save the new passphrase in KeePass but I honestly believe I saved it.
So, I guess I lost $1500 worth of Bitcoin. I only have one passphrase inside KeePass and it seems like I lost the one I overwrote it with. I tried all my backups and nothing works. Worst feeling ever. If anyone can successfully provide advice on how to get them back I will give them some BTC. My skype is media504
I had the exact same thing happen, specifically with keypass. Luckily I had no money in the wallet and was just trying to change the password. I now do the password change with the same password religiously. I am also considering moving to a non encrypted Wallet.dat file that I keep on a few USB pens, or a paper wallet.
I can suggest a few things, you might have used the wrong key combination and used your USERNAME from keypass. Also just try the passwords in keypass that you use a lot, you might have used one of those. It is worth trying.