As you can see from my question, I have a VLAN configuration problem with a ProCurve 3500. The goal is to remove a VLAN from the existing configuration, however when I use the WEB UI to do this, I cannot modify ports to be assigned to a different VLAN or the Default VLAN. I always get the message "config failed", which is not very helpful.
When I try to do it over telnet, the router somehow partially crashes and the utilization on all ports is at 100% and I can barely use the web ui. After a reboot everything is fine again, but the configuration was not changed. The traffic after this partial crash looks like a broadcast storm, however there are definitely no loops in the segment.
I also updated to the latest stable firmware, but the problem persists.