CRC errors can be attributed to packet collisions caused by any the following:
A dense population of client adapters
Overlapping Access Point (AP) coverage on a channel
High multipath conditions due to bounced signals
The presence of other 2.4-GHz signals from devices such as microwave ovens, wireless handset phones, etc.
The Physical Layer Convergence Protocol (PLCP) error counter totals the number of times the client adapter started to receive an 802.11 PLCP header, but the rest of the packet was ignored due to a Cyclic Redundancy Check (CRC) error in the header. Troubleshoot PLCP CRC errors as you would other radio frequency issues.