DHCP issues on Network

[stuckeysnewband]

Good Morning all,

I am having a real strange error that, I hope, somebody has suggestions/ideas/help on. My company recently installed 3 Cisco 24prt CE500s and 1 12prt CE500 Gig switch. We replaced several unmanaged switches. The are a couple of pocket switches out at users' desks. Occasionally, PC's on our network are not able to obtain IP addresses from our DHCP Servers(HP). The issue looks like a network infrastructure, but we can't pinpoint it. Has anyone had similar issues with CE500s?

[glen.grant]

Do you have spanning tree portfast turned for all "user" ports ?

[stuckeysnewband]

No they are not. This is happening when a lease expires, not just on bootup.

[noran01]

What is the logical flow from a PC experiencing the issue to the HP server serving DHCP? Is it a flat layer2 LAN or are there layer 3 devices in the mix?