Reload On Timeout ( click here to install ) is a very simplistic firefox extension ( add on ) that will reload any tab that has the title "Problem loading page".
It's a quick'n'dirty solution for handling slow and unreliable network connections.
The only user configurable option is the delay between attempts at reloading the failed pages/tabs.
I used a fabulous utility from Ted Mielczarek. His readme is below. See: http://ted.mielczarek.org/code/mozilla/extensionwiz/
Feel free to download the source code!