Really, it would be better if time.sleep was based off of a monotonic clock, then everything could use the single working API, and we wouldn't need to monkey-patch everything that uses sleep.

Unfortunately, due to the insanity that is the underlying Windows platform, the bios clock is set to local time and is converted to UTC (which is then used natively by NT).  There is a work-around involving setting the system clock to UTC and setting a registry setting, but it doesn't always work, can cause 100% CPU usage during DST changes, and doesn't propagate time changes from NT to the underlying clock.

http://www.cl.cam.ac.uk/~mgk25/mswish/ut-rtc.html

An alternate (or additional option) is to just disable DST changes, manually adjust times as necessary (or using a script that runs only at boot), and never run any software while adjusting the time.

http://www.pcreview.co.uk/forums/thread-531048-2.php

Considering the recent changes to DST, the latter link is probably more applicable.