Listen... I know you are going to think I am a kook and dismiss me out-of-hand, and if you are NOT intimately familiar with Bitcoin protocol and capable of coding an altcoin client, read no further (just please spare me the disparaging comments).

I think I have an idea on how to create an altcoin protocol (I'm dubbing it Zapcoin) that:
    - verifies in seconds;
    - does not require solving a puzzle as a proof-of-work;
    - is fully distributed à la Bitcoin;
    - employs no trusted party.

I know, it can't be done. Don't bother telling me. But if you meet the qualifications above, I'd love to talk to you offline. I think I could code a proof-of-concept client myself, but I just don't have the time. I'd love to share the idea confidentially with a capable, trustworthy coder. Together we could develop a simple client and try it out... who knows?

Here are some of my credentials: I have a 45-year career as a computer design engineer, working for Control Data, Elbit Computers Israel, Fibronics Israel, Honeywell, ADC Telecom, Lucent, Agere, Lattice Semi, Australian Semi, and currently my own startup; I have 4 patents and a patent pending; in my initial job, I was responsible for the floating-point divide unit on the CDC Star-100, the world's most powerful computer in its day (in the Guinness Book of World's Records as such). Through the years I have held top-secret clearances with DOE and FBI, and done some interesting stuff.

I've been fascinated with Bitcoin since I learned of it two years ago, and though I haven't tried mining, I bought a substantial amount of coin at $15, so I've done well.

As I say, only respond if you'd consider working with me, and be prepared to somehow demonstrate that I can trust you before expecting me to divulge details. me@zapcoin.org

I'm having a similar problem...
I've been verified at Mt. Gox since last August -- they even sent me a free Yubikey, and it's functional -- but I have been withdrawing my BTC funds into my personal cold storage. They have placed a BTC100 per day limit on my withdrawals (even though their records show that I'm verified). After I made withdrawals for several days, suddenly they declared that my "account is currently pending review" and referred me to the verification page. I tried to resubmit verification documents (they already had my passport & utility bill from last August), and got error messages that didn't allow me to continue. After a day of that, I finally got a message that my application was in the queue -- and I'm currently number 26820 in line! After a day, my position hasn't moved. I sent a message via their "contact us" page, and also to "alm@mtgox.com", but to no avail.
This doesn't look good...

That increase may be enough to save BTC. Let's hope. But it must occur before the financial community switches from viewing BTC as a "bubble" and sees their power being ripped out from under them.

You're right, the concept of stateless crypto-currency is out of the bag, and there is likely no way to put it back in. But I'd hate to see all the people that have invested time, sweat and blood into BTC v1 lose all, and a new crop of investors (the status quo financial crowd?) start up BTC v2, with them reaping all the rewards.

DeathAndTaxes, if methods exist to secure the blockchain from attack, they should be implemented now, not after the established financial community realizes the threat and reacts.

RodeoX, I think you are overestimating the computing power needed to take over the block chain, and underestimating the threat that BTC poses to the established financial community, both fiat currency providers and credit card/POS issuers.

The current hash rate is 63.686 THh/s, and a production mining rig does 50 GH/s. So with a mere 1200 commercial rigs, the entire current hash rate can be duplicated.

Do you think that these established players will let themselves be brought down when the cost is so small to bring BTC down?

BTW, I am an ASIC designer by trade, and have worked on the most powerful computers, used by Livermore Labs. I know what I'm talking about technically. It would be trivial.

This kind of attack, by a central bank or a large government, is the one that worries me. Even though such an attack requires a "HUGE" amount of computing power, it would be trivial for a large, threatened institution that is concerned, not in turning a buck, but in destroying BTC.

So let's say a group of nefarious miners consorted to place a fake block on the chain. Then there would be two blocks to follow... how do miners proceeding to the next block choose which fork to follow? When there are two possibilities, it would seem that it would be trivial for every miner to notice that there are two options and recalculate each one to select the correct one... oh yeah, half the minors (the nefarious ones) would select the fake block, and so on, eventually overpowering the true block.

Right?

We hear a lot about the possibility of a 51% (more accurately, 50%+) attack on BTC, but I don't understand what the attack requires 51% of. Is it the miners, and if so, is it 51% of the total hash rate? How is that determined and propagated? Do I then, as a BTC holder but not miner, have no influence on this? Or is it somehow tied to the total number of BTC in circulation?

Alternatively, the payout could be reduced by a factor of (the 1/48th root of 1/2) = 0.98566319864018757466759415575871 once a month. Anything would make it smoother.

Once you have the number, it's pretty easy to code.

Is there a reason why the reward for mining, currently 25 coins per 10 minutes, halves every 4 years, instead of decreasing smoothly?

Every   ((4 years) * (365.25 days/year) * (24 hours/day) * (6 payouts/hour)) = (210,384 payouts), the payout halves. Instead, the payout could be reduced by a factor of (the 1/210384th root of 1/2) = 0.99999670532911859551036168842216 every 10 minutes.

In this way, there would not be a huge jolt to the mining system every four years. Granted, the system survived its first jolt, but why have such a stress in the first place?

I'm sure this belongs in the Armory section, But I'm still a newbie...

I have enough BTC that I need to use Armory on an offline PC, so I set it all up and it works great. I assigned a good, strong password. Now, is my paper backup vulnerable to theft by a physical burglar, or is it useless without the password? Similarly, what if a physical burglar stole my offline PC?

Thanks in advance!  

Thanks, NothinG, for the -rescan tip. CTRL+F didn't work (is that feature dropped on newer builds?), but fortunately I had saved the previous Data Directory by renaming it, so I renamed it back and restarted bitcoin-qt.exe with "-rescan" on the command line. VOILA! in minutes instead of hours, it came up with the missing coins.

Thanks, too, to paraipan and others who provided tips. You're awesome!

In a few minutes, if no one tells me to do otherwise, I'm going to erase the blockchain and force a reload, but this time with the wallet already in place. I'll remove everything from the data directory and insert the wallet.dat file. Then I'll find out tomorrow if it worked.

LET ME KNOW IF I SHOULD DO SOMETHING ELSE!

The third PC (receiver) is running v0.8.1-beta and the sender is running v0.7.2-beta (I know, I need to update it soon).

Thanks for the reassurance, but it's been over a day, and the client doesn't seem to be doing anything. What is -rescan?

Yes, the address is still there... what is rescan? I'll look it up.

Address change is not automatic in all bitcoin clients (but it is advised that you create a new address for each transaction, for anonymity's sake). However, some clients do automatically create new addresses: Armory and Mt. Gox, for example. Bitcoin QT creates a pool of 100 (default value) addresses at startup, so that your backup will contain the first 100 transaction addresses. Make sure you back up more frequently than this.