I can't offer you any advice on your problem but This is what just happened to me.
I run wcp on two pc's. I use one to input the info and the other as a spare or floater that can go off to the accountant. A few weeks ago the spare laptop crashed, so I backed up to memory stick just to be safe.
I bought a new laptop and re-installed wcp, no worries there. I tried to update from the memory stick to the new laptop but got an error message. Stupidly I kicked my heels for a few days and did nothing about it. Since then the main laptop has gone down taking my entire business with it, as well as all the info for the latest tax return. I have been working from memory for the last two weeks.
Fortunatly the main one has been looked at by some hairy geek in a back alley and has come back in working order. I am now on strict instructions to lift everything off before the hardrive collapses completely.
Lucky escape, but a lot of head scratching as I now have a couple of weeks to update.