Download accelerators are pretty much a rip-off. They may also contain spy/adware. I would stay away from them.
http://www.gnutellaforums.com/showth...ht=accelerator

If you update to 4.12.10, there will be a big orange announcement at the top of your LW. It's there to warn people about downloading a bogus LW .exe update that's appearing in search results. So if you don't want to see that on your LW, stick with 4.12.6. If you do decide to update, you'll find that all of your options will revert to default after installing...so make sure to go through & reset things to the way you had them with the previous version (including days to keep incomplete files, that will revert back to 7 days!).

You might have an internal firewall within your modem/router. Can you give us your details please?
System details - help us to help you

*Don't run without a software firewall. Use only 1 & configure it to allow LW