Troubleshooting a Bad Internet Connection

For the past few months I've been plagued with sporadic dropped connections (XP/SP2 on Comcast cable, no routers or any fancy connections). I'll go a week with all OK, then get a dozen drops over two days, then three good days, then 3 drops per day for 2 days and then.... Comcast swears the cable/splitters are good, we replaced the Comcast modem twice, replaced the modem>NIC cable, and ran AV/Malware programs several times. In all cases, a simple reset of the modem and a PC restart solves the problem (until the next time).

Is there any way to "prove" that it's a Comcast problem (modem to head end) and not my PC? I can monitor the modem's signal strength; Transmit typically 45-48 dBmV, Receive typically 0.5-1.0 dBmV, altho I've experienced -1.0 or -0.8 at times. Device manager indicates my NIC card is OK, even if the connection is partially down (the crash usually occurs in steps; #1 the connection goes down but the cable icon says it's connected; #2 a PC restart..with no modem reset..then results in the "cable unplugged" balloon). If I try to repair the connection thru the network icon, I get a message to contact my ISP so as to get a network address. My email client, Eudora, leaves messages with the flavor that my ISP hasn't got an IP address for me, or that I can't communicate with my ISP's server. This seems it's maybe a protocol problem, that the handshake between me and Comcast keeps getting cut off (that's why I've been watching signal strength).

If I could just pin this on Comcast, I could make a fuss. They say it's my NIC (it's very inconvenient for me to swap NIC cards, so I'd rather avoid that route if I can). I really doubt it's the NIC, Device Manager has never indicated a problem with NIC (and I guess I'd expect the problem to not be so sporadic if it was NIC)

Any ideas/insights would be greatly appreciated.

 

Hi chrisw, Have you tried updating the drivers? Neil.

 

Neil...yep, did that too...didn't help. Thnx, Chris