Problem with new WAN connection and HP3500

[red-umbrella]

I currently have a Metro-E 100mb connection, handed-off from my telco's Cisco equipment to my core switch, a Procurve 3500.  This has been working well for years.  On the other end is another 3500.  Between the two I created a VLAN for the branch office.  The port on the core 3500 is tagged in the branch VLAN.  It is also untagged on the default VLAN.

So, the same telco has given me a new WAN connection.  This new connection is different in that it represents 4 total sites.  It is also on a different network they tell me.

I set it up exactly the same way as the working Metro-E, but when I do, it has now twice taken down sites.  The 1st time it took down the old Metro-E as well as some T1 sites.  The 2nd time, it took down all of my T1s (3) which all went down at exactly the same time.  I immediately unplugged it, and it took them 5 minutes to come back.

Searching logs, syslogs, events, etc. shows no loops.  Loop protect shows no loops.  I might have missed something, but all appears normal.

The only thing I did find is where, on the 1st time it happened, the port I plugged into spit out a dozen lines showing the Mac Address at one of the T1 sites as now listed on that port in addrmgrmovelist.

Here it is:

0015c2-450758      1      23         22      05/24/14 15:10:43
0015c2-450758      1      22         23      05/24/14 15:10:43
0015c2-450758      1      23         22      05/24/14 15:10:57
0015c2-450758      1      22         23      05/24/14 15:10:57
0015c2-450758      1      23         22      05/24/14 15:11:09
0015c2-450758      1      22         23      05/24/14 15:11:09
0015c2-450758      1      23         22      05/24/14 15:11:19
0015c2-450758      1      22         23      05/24/14 15:11:19
0015c2-450758      1      24         22      05/24/14 15:12:37
0015c2-450758      1      22         24      05/24/14 15:12:37
0015c2-450758      1      24         22      05/24/14 15:12:53
0015c2-450758      1      22         24      05/24/14 15:12:53
0015c2-450758      1      24         22      05/24/14 15:13:11
0015c2-450758      1      22         24      05/24/14 15:13:11

Do I simply need to take port 22 -- the new WAN connection -- and untag it to a VLAN that's not the default?

I'm honestly baffeled as to why this is happening.  The telco is telling me it is my equipment.