Another date problem, which results from computing dates into the year 2038 and beyond in 32-bit operating systems. Unix and other C applications represent time as the number of seconds from January 1, 1970. The 32-bit variable (time_t) that stores this number overflows in the year 2038 and becomes January 1, 1970 again. However, even today, any date calculations forecasted beyond that time will be erroneous. Switching to 64-bit computing solves the problem. See Y2K problem.
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The year 2038 problem (also known as Unix Millennium Bug, Y2K38 or Y2.038K by analogy to the Y2K problem) may cause some computer software to fail before, in the year 2038 or after. The problem affects all software and systems that both store system time as a signed 32-bit integer, and interpret this number as the number of seconds since 00:00:00 UTC on Thursday, 1 January 1970.[1] The furthest time that can be represented this way is 03:14:07 UTC on Tuesday, 19 January 2038.[2] Times beyond this moment will "wrap around" and be stored internally as a negative number, which these systems will interpret as a date in 1901 rather than 2038. This will likely cause problems for users of these systems due to erroneous calculations.
Further, while most programs will only be affected in or very close to 2038, programs that work with future dates will begin to run into problems much sooner. For example, a program that works with dates 20 years in the future will have to be fixed no later than in 2018.
Because most 32-bit Unix-like systems store and manipulate time in this format, it is usually called Unix time, and so the year 2038 problem is often referred to as the Unix Millennium Bug. However, any other non-Unix operating systems and software that store and manipulate time this way will be just as vulnerable.
Read more: http://www.answers.com/topic/year-2038-problem#ixzz198j0oK00