What does it display when it fails to ping the two addresses through the DOS prompt?
Microsoft(R) Windows NT(TM)
(C) Copyright 1985-1996 Microsoft Corp.
H:\>ping ash.unl.ac.uk
Pinging ash.unl.ac.uk [163.167.84.6] with 32 bytes of data:
Request timed out.
Request timed out.
Request timed out.
Request timed out.
H:\>
Microsoft(R) Windows NT(TM)
(C) Copyright 1985-1996 Microsoft Corp.
H:\>ping
www.ionactive.co.uk
Pinging
www.ionactive.co.uk [213.171.218.12] with 32 bytes of data:
Request timed out.
Request timed out.
Request timed out.
Request timed out.
H:\>
If it looks like the above then this is normal, and would just indicate that the address is actually refusing to acknowledge the request for a PING reply the same as a firewall does.
HTH