Hi Matt,
sometimes it's hard to find the correct break combination to boot into single user mode. For me it took some time to find it on a Swedish keyboard layout as the Cisco documentation only says ctrl+].
To verify correct break character run telnet in a MS DOS window. A correct break would break the session and produce a message like "Welcome to Microsoft Telnet client...".So you could just test all possible keyboard combinations until you have the right one. Then just follow the correct password recovery procedure:
http://cisco.com/en/US/products/hw/ps4159/ps4358/prod_password_recoveries_list.html
You need to get to the switch(boot)# prompt to reset password. Press ctrl+] exactly when you see "Loading system software". The message "Switching to runlevel: 1" indicates you are entering switch(boot)# prompt.
Rgds Filiph
CCIE #25916