Can’t ping or telnet

Folks,

I have a lan with a 23 bit mask and 5 cisco 2950 switches and at the core a 4006 switch which connects to a 7000 series router as the gateway.

My problem:

From a node on the lan i can ping the gateway but no-one of the switches. I can ping out of the lan to other lans successfully

From the console of any of the switches i can ping the other switches and see them all using Cisco CDP – I can also telnet to other switches.

All switches have the gateway set as the ip default gateway.

Any ideas why i can’t ping from any of the lan nodes or telnet to my switches?

Any suggestions gratefully received

thanks