Downloading Stalls


I have an iMac G4 connected via ethernet cable to a router. A few months ago I began to experience problems when downloading large files. The browser or FTP program would load for a while, then stall. A few smaller files will usually download OK.

When the problem first arose I was running 10.2.8. I have since done an erase and install with Tiger, but the problem persists. If anything, it is slightly worse.

I ran the hardware diagnostic CD that came with the computer. No problems were reported.

When another computer is plugged into the ethernet cable it is able to download normally. Also, my wife's iBook has no trouble downloading via Airport connection to the same router. Our ISP tech came today and confirmed there is no problem with the cable modem. This suggests that the problem is with my computer rather than the connection.

I have two questions:

1. Do you have any idea what may be causing this problem?

2. Do you think installing an Airport card, thus bypassing the ethernet port, would resolve the problem?

Many thanks.