PPPoE and Windows

Newly installed uBR7246vxr.....working great all except for some reason people using Windows Vista/7 PPPoE frequently disconnects like every minute.

If they are using a router, no problem stays log in. It is happening on different computers, on different ports. I can't even duplicate the problem. I thought it might be malware causing it, but that does not appear to be the issue. I've switched out modems, levels are good, modems aren't losing connection to the CMTS, just PPPoE sessions.

Sun Jan 8 10:04:18 2012 : Auth: Login OK: [xxx] (from client cmtsrouter port 0)
Sun Jan 8 10:05:30 2012 : Auth: Login OK: [xxx] (from client cmtsrouter port 0)
Sun Jan 8 10:06:10 2012 : Auth: Login OK: [xxx] (from client cmtsrouter port 0)
Sun Jan 8 10:07:54 2012 : Auth: Login OK: [xxx] (from client cmtsrouter port 0)

Is there a keepalive or other setting I should have in the config?

cable config-file standard.cm
service-class 1 max-upstream 1000
service-class 1 guaranteed-upstream 256
service-class 1 max-downstream 7000
service-class 1 max-burst 1500
cpe max 1
timestamp
!
!
vpdn-group cablemodem
accept-dialin
protocol pppoe
virtual-template 1
pppoe limit per-mac 1
pppoe limit per-vlan 250
!
!
interface Virtual-Template1
ip unnumbered GigabitEthernet0/1
ip access-group 164 in
ip access-group 160 out
ip verify unicast reverse-path
no ip redirects
no ip unreachables
no ip proxy-arp
ip mtu 1492
ip tcp adjust-mss 1428
no logging event link-status
peer default ip address pool cablemodem
ppp mtu adaptive
ppp authentication pap chap

Thanks for any help in advance!