If you have a lot of money saved in your current 401k, NOW is a good time to change jobs IF you are sure you'll have at least as much job security in your new job, BECAUSE you can move your 401k into a "rollover 401k" account tax free. Let me explain. (You open a "rollover 401k" account in a brokerage and continute to manage your money, though you can't contribute to it. It will be independent of your new employers 401k.
The typical 401k has NO PROTECTION against a hyperinflationary crash. There are typically NO choices available that are safe against simulataneous INFLATION and a worldwide stock market crash.
We WILL have massive inflation over the next few years because of the bailouts. Whenever the Fed loans money it CREATES it out of nothing, diluting the existing money supply, creating inflation. This is how our monetary system works. The Fed has recently expanded the monetary base at unprecedented amounts.
If you keep your money in cash over the next several years, it WILL be severely eroded by inflation.
Typical ways to protect your money include foreign currency accounts, foreign currency bonds, and gold. The typical 401k account does NOT have these options. The typical brokerage that can host a "rollover 401k" account DOES.