I can make my PDANet lockup and/or drop my connection pretty much on command. Here's what I sent to support, but I figured I'd post it here to see if I could get some better help.

I am running a registered copy of PDANet for windows mobile on a Treo
700wx to tether to my laptop running Windows XP with the USB cable.
Every time I attempt to download a decently sized file (more than a
couple of meg's), one of several things happens, but they happen
without fail.
1. My connection simply disappears and I have to press reconnect.
2. My connection seems to remain active, however, I am not receiving
any packets. Upon further investigation, I find that PDANet has locked
up on my phone and I have to either close/restart it, or soft reset my
device.
3. my connection disappears and PDANet on the computer locks up and I
have to manually kill the process through task manager. Occasionally
this causes the modem to lock up, and I have to reboot the entire PC
to fix it.

Sometimes 2 and 3 happen at the same time, but something goes wrong
EVERY time I try to download something either through a web page or
through an application such as Steam.

I'm looking for some help getting the connection to be more reliable,
as I am in love with the software and the way it allows me to browse
the web and IM on the go.