I'm in C portability hell with Time::y2038. The code to test the usable limits of the system time functions is touching off all sorts of fascinating bugs in various operating systems, many of which cause the test program to hang.
Oh, and then there's reports that "old" (read 2002) versions of Visual C++ don't speak C99 but some Microsoft extension gibberish. And, of course, Vista problems.
C: Fast, elegant, portable. Pick any one.
Also I need to add in code to test the limits of the system's mktime() and I haven't devised a sensible way to do that. I suppose I have to do a binary search over the year, then month, day, hour, minute and second. Oi, not fun in C. Maybe I'll just do it by year, that's really all the granularity I need.