Create a new wallet and if that loads it sounds like the wallet is corrupted. Is it possible you were quick one day ? Maybe the memory stick is having a problem.
To be extra sure you could load the wallet in the client running on another pc ?
Otherwise get the backup, backup the backup, and hopefully you can stop worrying.
hi, I loaded a new wallet ok on the block chain.however when i said my back up was difficult to get i meant it was in another country! i also think maybe when i exited the client maybe it had not finished closing properly? i will see if the new wallet.dat reloads properly since i waited this time before copying it to the memory stick. but if that was the problem i cant access my back up any time soon. the corrupt file is still there and is a green circle of arrows and called-wallet.13925404.bak- i searched the forum and believe there are methods to restart with a restore wallet command line but i do not know how to use it. if you know where i could find a method suitable for a non tech person (me) perhaps i could try that. thanks for your reply.