What's wrong with it!? Agh!

It's my dad's machine again...

Everything has been fine since the reformat, except connectivity rates, which rarely rise above 14.4kbps on a 56k modem. My laptop pulled 44kbps today when I tested the line he uses.

Funny thing is, his machine connects at 36kbps or higher when he uses a different line. We've tried three different modems in his machine, and all of them can barely hold 14.4kbps on his dedicated line, but like I just said, when he uses another line, they all connect at 36k or higher. My machine and my laptop can use his dedicated line with no problems.

To simplify things:

His line:
-Dad's machine hates it
-Laptop works fine
-My machine works fine

Another line:
-Dad's machine works fine
-Laptop works fine
-My machine works fine

It appears his machine dislikes using that line, and only that line, while all the other machines have no problem with it. What can we do to fix this, short of ripping out and replacing the phone line all together? I am completely stumped as to what his problem is.

do you use the same cable between your dads and the wall and the laptop and the wall, and same jack?

Odd - what about port speed settings in hardware manager? Internal or external modem?

It's an internal modem, and no, we didn't use the same cable on the laptop. We used the same cable on the other lines, though... worked fine.

So your dad's machine likes one tele line fine, and not another? Concurrently your machine has no problem with the line that your dad's system doesn't like? Is the wall jack loose? Try different cables? Anything else running on that line your dad's system doesn't like - splitters, etc?

We've replaced the wall jack, checked the phone box by the road, run multiple line tests, tried different modem commands, different cables, feng shu, everything short of ripping out the actual phone line from the house to the road.

No splitters, either. Straight from the modem to the wall.

Are you Catholic?

Methodist.

Hmm, guess that rules out an exorcism