According to most reports and my dealing with them, SBC has very little idea
what they are doing. Outlook could not cause intermittent errors, it either
works or it does not. Tell SBC to do a loopback test on your line with and
without your modem. Or try to get them to change the routing circuit. Most
likely you have noise on your line that is messing up the DSL signal.
One thing, you do not have any of the filters or surge suppressors plugged
into your DSL line that goes to your modem do you ? These are fine to use on
the phone connection, but not on the cable the DSL is on.
Hope that helps and good luck..