|I asked what I did because I've never heard of a modem that was capable of "bridging".|
One uses to a bridge to aggregate two (or more) networks into one big network.
A modem is simply a device that modulates/demodulates a signal. Which is to say, takes your ADSL from a telephone wire (a single pair) and puts it on a network cable (4 pairs) and vice versa.
Unless this is a combo device (ie: combination modem/router/wireless access point) it shouldn't even be capable of bridging as modems are not designed to do that.
I suspect it's whatever you did when putting said modem into "bridging" mode that is preventing it from working with the Linksys router. Or at least, without more info about what was done and the capabilities of the modem, that's all I can offer as a guess as to what's going on.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.