Unix Millenium Bug

http://en.wikipedia.org/wiki/Year_2038_problem

The year 2038 problem may cause some computer software to fail at some point near the year 2038. 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 is caused by integer overflow. The counter “runs out” of usable digits, “increments” the sign bit instead, and reports a maximally negative number (continuing to count up, toward zero). This is likely to cause problems for users of these systems due to erroneous calculations.