A serial data transfer gone wrong. See this to understand the mechanism (at least the recepter) : http://www.youtube.com/watch?v=gqryvkOpOJ0 (properinglish19)

What I expected to happen was...:
A inverted one tick pulse "unBUDs" a piston, updated by a comparator. Said piston retracts, depowering the redstone piece below the attached redstone block. The torch on the redstone piece's block then activates after a tick, powering the block above back to it's source wich in turn deactivate the torch one tick after, and before it can repeat the redstone block is pushed back in place.
There's a serie of these, one tick apart.

The data line then feeds into the recepters as shown in the video above (only the timings and emeters are different).

What actually happened was...:
When placing the first 6 redstone blocks (the upper ones to prevent a pulse and write a 0) from right to left as shown in screenshots, the fifth bit is made a 1 in place of a 0. Place a redstone block in 6th bit and the 5th is a 0 again.

Steps to reproduce:
Screenshots should hopefully be enough to reproduce it. Don't mess up the timing, it's important.