VPN connection setup damaged (Windows)

I use VPN part time to connect to the office. Within the last week, on two different PCs (XP and 2000 Professional), connection setup has broken on both PCs. It connects, but there is no "bubble" saying it has connected, no taskbar icon (I have it set to display one), and the only option I can get is "connect" - and I have to go into network connections to get this. So I have to log off to disconnect from VPN.

On one PC (XP) the icon mysteriously reappears when I log in again, and VPN is still connected. I now have the option to disconnect. However when I do, the icon remains on the taskbar, and although the connection is dropped, the only option now available remains "disconnect". Therefore I have to reboot before I can use VPN again.

On the other PC (2000 Professional), the VPN connection is dropped, and I can connect again. However I still have the problem that I can't disconnect withoug logging off again.

Very odd. It's as if something has become damaged or corrupted. But for it to happen on two different PCs must be more than a coincidence. The only thing that I can think of is that it could be something to do with upgrading my BOINC software. However this problem hasn't occurred on a third PC (2000 Server) - yet . Any suggestions please?