Not much familiarity with Mac's but here's the issue:

The computer is connected to the net. Can access google, gmail, etc. but cannot access youtube, myspace... On first appearances it seemed that there was a content guardian or something running but that's not the case. Can access adult websites. Can sometimes download, ie. could access divX and download but not realplayer for mac. Error returned is:

Cannot connect to the server.

Can ping www.google.com but pinging www.myspace.com returns:
ping: sendto: No route to host.

Problem is not connection related as it's happening on different LANs.

Possibly something obvious to Mac users but it's my first run-in ...

What’s the output of “route”?

What parameters / arguments should I give?

I am experiencing the same as Broder. With a ping to myspace I have the same result.

As for traceroute, this is what returns:

traceroute: Warning: www.myspace.com has multiple addresses; using 216.178.39.15
traceroute to www.myspace.com (216.178.39.15), 64 hops max, 40 byte packets
traceroute: sendto: No route to host
1 traceroute: wrote www.myspace.com 40 chars, ret=-1
*traceroute: sendto: No route to host
traceroute: wrote www.myspace.com 40 chars, ret=-1
*traceroute: sendto: No route to host
traceroute: wrote www.myspace.com 40 chars, ret=-1
*traceroute: sendto: No route to host

...and so on and so on...

I am able to access these sites from a windows machine which is connected to the same router, so the cause is undoubtedly located somewhere within OS X.

Any suggestions? Thanks in advance.