There's a bunch of ARP packets that apparently indicate that 26 doesn't know where 34 is. I think (and I'm no expert) that it doesn't know which MAC address has that IP. Pings to 42 come straight back with no need for ARP because its MAC is known to 26.
I think that either you're reusing a MAC address or your router has a conflict between DHCP and the static IP addresses you have assigned.
What is the first IP address your router can issue through DHCP?