That's why I was opposed to the pseudo-privatization schemes Bush had in mind for Social Security. The only answer is to dump the program like the Ponzi scheme that it is.
You have to fund today's seniors though, which is why SS should be gradually phased out. Force younger workers to invest a minimum of 10% annually into their own private IRA, and give middle-aged workers to opt out of the program completely in exchange for having what they put into the system rolled over into an IRA or 401(k). Dump it entirely and you'll see rioting and anarchy in the streets.