I would check these things:
1) Do you have a forwarding IP VIP. I just used a any any Forwarding VIP.
2) I don't think it would be rejecting it due to a checksum, but possibly a missing route. Make sure you have proper routes to reach your Connection Servers and make sure they have proper routes to reach the F5. Windows Server does not have telnet by default, but turn it on or use putty, to telnet to the F5 using 4172 and make sure it's open.
3) Use the "sessiondump" on the CLI when logging in for troubleshooting to see how far the user is getting.
4) And most importantly, in Vmware Horizon View, double check your PCoIP Secure Gateway. Vmware strongly recommends you use a seperate NAT (Public IP) I know, I know, you are supposed to be able to go back through the F5 for everything, but you may want to cut your loses and test this.