So I store my wallet.dat files offline in a truecrypt file. When I want to send BTC I shutdown the bitcoin.exe app and swap out the wallet.dat file. And then run a -rescan to load up the updated wallet.dat file.
This process has been working fine for some time now. But now all of a sudden, I can't get the client to accept any of my stored wallet.dat files without giving an error and crashing.
Error I get when I try and load up a stored wallet.dat file:
Db::open: Invalid argument
C:\Program Files (x86)\Bitcoin\bitcoin.exe in AppInit()
If I then delete my backed up wallet.dat, and launch the bitcoin.exe app again, it creates a new fresh wallet.dat file without any errors.
I've tried deleting the block chain, and re-downloading from scratch, but it doesn't work.
I've tried wiping all traces of the bitcoin client from the system, and doing a fresh install, and still no luck.
Any other ideas I have missed?