I've recently replaced a 3Com 3300 switch to a 3Com 4400 switch.
After this there are some strange login problems.
Generally the login process is slower on the 4400 switch and
after hitting Ctrl+Alt+Del on the workstation and then click on the Trees button the WS will not find any tree.
The login will however succeed but will take longer time than on the 3300 switch.
The reason for this problem is that the 4400 switch has "IGMP Multicast Filtering" enabled by default.
The 3300 switch has this disabled by default.
So to get normal login speed turn off Multicast filtering.
After this there are some strange login problems.
Generally the login process is slower on the 4400 switch and
after hitting Ctrl+Alt+Del on the workstation and then click on the Trees button the WS will not find any tree.
The login will however succeed but will take longer time than on the 3300 switch.
The reason for this problem is that the 4400 switch has "IGMP Multicast Filtering" enabled by default.
The 3300 switch has this disabled by default.
So to get normal login speed turn off Multicast filtering.