Strange modem behaviour

[Bill LaGrue]

Hi All
Until recently, I had been using a Huawei E220 UMTS modem for my mobile
broadband. It had been working perfectly, but now a strange problem has
crept in somewhere. When I connect, after about 15-20 seconds after
making a successful connection, the GNOME toolbars become unresponsive,
however icons on the desktop and windows that are already open still
work. I can also still right click to bring up context menus. About
15-20 seconds after that, the whole desktop becomes unresponsive -
nothing works, except that the mouse pointer still moves - no buttons
though.
Its really got me baffled as to what could be causing this. I have
tried the Huawei E220 (USB) and also a Novatel Merlin U630 (PCMCIA)
modem, and on the dialler side, Vodafone Mobile Card Connect (which I
usually use) and UMTSMON. The same problem occurs regardless of the
modem or software. Connecting to the internet via the 'regular'
wireless network still works fine, so this leads me to think the
problem is with pppd or possibly wvdial and/or chat.
I am using F8, latest updates, no exotic/3rd party drivers. I was using
the ATI supplied divers but removed them, just to make sure.
Anyone have any suggestions?

-- 
bill at billlagr.id.au