I have had success with scanning utilizing a Twain driver on a 1060. Here are some things to consider.
Personal Firewall Software may be blocking communication on the port that Twain uses to communicate...XP for example has a built-in firewall that will block ports used for various service communications...Port 1022 is used for Twain communication....You can check to see if your pc is "Listening" on 1022 by running netstat -a at a command prompt...
Try disabling SNMP on the network interface...I have seen this protocol do some strange things in regards to scanning...