Which version of LW are you using? If you're using LW 4, see below.

Go into your account, open LW & go tools > options > advanced > firewall. Make a note of LW's listening port. Close LW.

The listening ports on your account & your Dad's account need to be different.

Go into your Dad's account, open LW & go tools > options > advanced > firewall. Change your Dad's listening port to 65000 (as long as the listening port on your account wasn't 65000) > apply > ok.

Restart your computer. Now see whether things are any better

If you're using LW 5 then please let us know, because the options are different in the new version.

The version of LW I'm using is 4.12.3 Pro. The ports are different when I check them, so unfourtunatly that wasn't the problem. But thanks for the suggestions.

Ah, ok. Often, when some accounts do work & one doesn't, it's a port issue.

Go into your Dad's account & find his gnutella.net file, Hover the cursor over that file - how big is the file?
The thread below has a section about deleting/replacing gnutella.net - that will explain to you where the file is & how to find it: If LW Will Not Connect

Also, try deleting LW's preferences folder in your Dad's account - the help thread has detailed instructions for that.

Feel free to try any fixes in that help thread as well! If you're still stuck, please could you post back with your system details? The help thread has a link with info about the details that we need (bottom of thread)