Try changing ports. In LW tools > options > advanced > firewall config. Change LW's listening port to something in the range of 49152 - 65535, try port 64049 for starters. Apply > ok.

Also in LW file > disconnect. Wait 5 minutes, file > connect.

Looks like Mediacom also offer a firewall in their security suite.
Mediacom Cable Service | Internet, Digital Telephone and Television | Broadbandinfo.com
Is there any chance that you have this firewall but just weren't aware of it??

This page says that the modem has a firewall...
Thomson - Cable - DCM 425 - Digital Cable Modem
...but I can't find any info, even in the user guide, about that firewall. You could try contacting Thomson, they might be able to give you some more info.
Thomson – Images & Beyond – A World Leader in Digital Video Technologies - Contacts

When you originally deleted LW's preferences folder, did you make sure that LW was properly closed at the time? Did all of your settings within LW's tools > options change after deleting that folder?? Did you also look for a preferences folder in the old location of C:\Documents and Settings\your username\.lilmewire?

Going to merge this thread onto your original thread...otherwise it's just too hard for people to figure out what WW's suggested before & what fixes you've already tried!!