If I have time in the next day or two I'll revisit this... but I'd have thought if there was a problem someone would have mentioned it in the eight years it's been around.

Despite the fact it's incorrect - is the Time incrementing?

Looks to me like the Data to/from the RTC is corrupt.

You got correct pull-up's on the CLK and Data lines to the RTC?

Download a fresh source copy and recompile... you may have changed something accidentally without noticing.