Streaming Strangeness

I have a WGR314Lv8 with DD-WRT std build 13064 (dd-wrt.v24_std_generic.bin).

 Everything seems to work fine except accessing large files from a network share over wireless (via a netbook).

 If I try and copy a large file or stream ANY video file, the wireless connection on the netbook is lost.

 I can stream music fine (even quite large mixes) but even clicking on a video file on a remote share can cause the wireless to drop.

 It worked fine on the cheap POS Azurewave router I used before so I am thinking the problem is on the router/dd-wrt end.

 Any advice very gratefully received.

Gary