Put the summary of the bug you're having here

What I expected to happen was...:
Well, i was playing with a friend via lan, we expected redstone systems to work

What actually happened was...:
The redstone systems randomly dissapear as in all the redstone and repeaters and doors become items. this is very annoying

Steps to Reproduce:
1. play minecraft via lan
2. build a redstone system for a piston door (example)
3. play for some time and the bug will happen