Trouble with File Transfer on Linksys

[CP]

I am having trouble transfering large amounts of date on my linksys wrt54G broadband router. I have a G card in my laptop. The router and card work great for internet and sending documents to the printer. I can transfer small amounts of date (2-300kb), but much larger and the laptop card losses the "network connection". It immediatly finds it again. I can watch the signal strength bar drop and the transfer stops, then it immediatly goes back to a good singal. Does anyone have any suggestions on what is casusing this?

Thanks
Chris