ATM ADSL

We recently purchased 2 Acer 520 and 1 730 series laptops and connected them to a Digicom modem blaster 7410 USB ADSL modem. They all work but the 520’s will disconnect from the modem without reason-like the connection timed out. The modem stays trained on the line like it is okay. Anyone know of settings in Internet Explorer that would cause this problem. Any tips appreciated!