Well, the memory mystery may not yet be solved, but it seems that I've FINALLY solved my connection problems with UT's internet servers. My modem was mysteriously dropping the line after about 30-45 seconds at anything above 19.2Kbd. I upgraded the modem to the latest b17 firmware from Supra and it's been FLAWLESS since then. I've had record transfer rates and I've even connected at 31.1 kbd (31/28). Much faster than before!
I highly recommend this update to anyone who is experiencing similar difficulties with their Supra's. I haven't noticed any other problems with this firmware update.