fedora 3 sending out invalid packets

Ok, so I said I had fedora 3 in my subject, but I'm not really sure what I have. I installed fedora 2, and then tried to do a yum update to fc3. It got stuck somewhere in xorg fonts I think. I then put in the fc3 dvd and did an update, and that finished, but x didn't work. But that's not the point. The point is that I'm running ettercap (ON MY OWN NETWORK) from a debian box, and I'm getting this:

Invalid TCP packet from x.x.x.108:139 : csum [0x6dfb] should be (0x9caa)
Invalid TCP packet from x.x.x.108:139 : csum [0x6df7] should be (0x615f)
Invalid TCP packet from x.x.x.108:32787 : csum [0x90ab] should be (0x129b)
Invalid TCP packet from x.x.x.108:32787 : csum [0x9095] should be (0x1df9)
Invalid TCP packet from x.x.x.108:139 : csum [0x6de0] should be (0xed74)
Invalid TCP packet from x.x.x.108:139 : csum [0x6de4] should be (0xa81b)
Invalid UDP packet from x.x.x.108:138 : csum [0x6e80] should be (0x11fa)
Invalid UDP packet from x.x.x.108:137 : csum [0x6e3a] should be (0xb031)
Invalid UDP packet from x.x.x.108:137 : csum [0x6e3a] should be (0x92e)

Those ports are samba (right?) and then something else, but anyways the point is, what do I do and does this error matter?
-ben