Connection problems

I'm having trouble staying on line. The problem started a couple of days ago. I connect with a broadband dongle. Sometimes it's disconnecting me after a couple of minutes - other times I'm OK for a couple of hours. No problem getting back on-line - only takes a minute, but it's damned annoying.

I contacted the ISP (Indian call centre) and they were of no help. Said they could see the frequent disconnections but that there was no breaks in their service.
I've been with them for 2 years and this is the first trouble I've had.

So - I'm hoping one of you guys can suggest something. I've tried a system restore to back before the problem started. I've run virus checks. I've taken the sim card out of the dongle and put it back. I've tried the dongle in other USB ports.

Anything else I can try ??

Do you hear the USB connection sound from the computer when you plug the dongle in? And the removal sound when you unplug it?

If you hear those sounds at other times, then you have a bad USB port OR a bad dongle. If not, then most likely the dongle is bad.

I hear the sounds you refer to only when connecting and disconnecting. Can a dongle suddenly go 'bad' ? I've been using it for about 2 years without a problem.

When I lose connection, the ISP's window still shows me as connected and the dongle's blue light is still lit and steady.