FCP crasheing when scanning clips in Log and Transfer

I'm running FCP 7.0.3 Hardware: Mac Pro 3GHz Dual, Mac OS X (10.6.4), 14GB RAM - ATI Radeon X1900 XT

I copy and back up all my AVCHD files using Shotput Pro, then transfer directly from my RAID. All good.

I'm finding that when I attempt to scan through a clip in the player window of L + T (manually moving the play head along the timeline) FCP frequently crashes. Any ideas why? Even better, any suggestions as to how I can stop it happening?!

Many thanks.