Hi Phil 169,
Are you logging out of each user account fully before logging into the next one, or using the "Switch User" option within Windows? The latter will keep the previous user account running in the background, along with all open applications, so the Vodafone Mobile Connect software would be locked out, along with the modem, as it would already be in use with the first account.
If that's not the case, and as you say, it's only happening with one account - it sounds like your Personal Account may not have full administrator rights on your machine. In order for the software to function, it must have full admin rights both during installation, and when making the first connection to the internet.
When you tell the software to connect for the first time, it writes a dial-up connection setting and places it under "Network Connections" in Windows. If the dial-up connection is missing, then you simply need to give your personal account full admin rights - tell the software to connect - and after this has been successful, you can lower it back to the original priviledges again.
Let me know if this helps in any way
Jon
eForum Team