Dropped packets pinging local switch

I am getting anywhere between 10 and 40% pinging my local managed switch.
I have swapped cables, switch ports and NICs. When I use the same cables
and NICs in a different machine I get 0 packet loss.

The switch is reporting tons of CRC errors and runt packets during normal
web browsing. I have tried tried the a 3C905, 3C905B and a FA311. All
experience high amounts of dropped packets.

The other PCI adapters I have in the machine are 2 x Promise PDC20268 and
a generic Trident video adapter. Currently running RH9 with stock i686
kernel.

Any suggestions on troubleshooting would be helpful.

Thanks,
Kevin