Sounds like a problem with your network hardware. Either your cable(s) or your router. You can identify a faulty cable by replacing it or swapping it with one you know is good. You need to consider the cable from your computer to the router AND the cable from the router to the target computer. One or both could be bad. If all of the cables check out, I'd go after the router next.
Whenever data is sent from one device to another, it generally passes through some number of intermediate devices (i.e. media -> disc drive -> cable -> port on computer -> i/o control software -> memory in computer). At any one of these points, there is the potential for information to be lost.
To solve this problem, a protocol was invented called "Cyclic Redundancy Check" or CRC. Accordingly, every time data is stored on any kind of media, some redundancy information is stored along wih it. Whenever information is moved from one location to another, the CRC bits tag along. There is always software or firmware at the receiving end to check that this redundancy information is correct. If not, a CRC error is generated (after some number of retries).
If a CRC error occurs, it usually means that data was lost or altered somewhere between the place that it began and where it ended up.
To fix this problem, you have to find out where the data is being lost or corrupted. This means testing each of the things the data passes through in its journey. Typically, this means swapping out each component in the chain until the CRC error goes away.