Make sure that LW's being allowed thru the Windows firewall.
User Cant Connect - LimeWire

Also check that you don't have a Windstream firewall running...this Windstream user had a problem with their firewall.
Cant Connect

Were you using the latest Java when LW was working? Some people have had connection problems with Java 1.6.0_02.Try this version instead. Use the JRE offline installer & remove your current Java version(s) before installing this one.
Archive: Download Java 2 Platform Standard Edition (J2SE) 5.0 Update 11

If that doesn't help, delete LW's preferences folder when LW's properly closed. See point 3 here & also point 2 if you've used older versions of LW in the past (there could be a folder in either location).
Fixes for LimeWire
This will kill all of your settings within options, you'll have to go back through afterwards & reset things. If you're not sure of your settings, go through LW's tools > options & write them all down, so that you can reset things later.

If you're still stuck...try port forwarding for your Speedstream. The instructions are here.
Port Forwarding for the Siemens 4200
Don't forget to set up a static IP address, or port forwarding won't work. Make sure that LW's listening port, port in the 'manual port forward' box & port forwarded within the router are the same number