HP 1910 802.1x authenticates, then drops

[Grove123]

I'm used to working with 5400, 2910 switches and the CLI. I've tried to set up our 802.1x/RADIUS on a 1910-8 switch in an outbuilding, and it almost works.

On a windows 7 client I connect cable, enter credentials and I get placed on the appropriate VLAN for my userID, get valid DHCP address for my subnet.

Everything works for about 100-120 seconds, then the switch puts the port back onto the unauth vlan number and client computer can no longer connect unless you release DHCP and renew, then it gets an IP on the unauth(quarantine) vlan.

plugging/unplugging usually restores authorized service - again for about 100-120 seconds.

The client doesn't appear aware that anything changed, but a continuous ping will fail after the 120 seconds.

The RADIUS/802.1x/AAA works on all our 5400/8200/29xx wired clients and our WiFi.

Any ideas?

Thanks