I don't know why they aren't working; however you can try to run them in a
different compatibility mode to see if that solves your problem. I've had to
do this with several games.
Right click on the Icon
Click Compatibility
Change to Windows XP (SP2) if this is what you had while it was working
Click Ok
Run the application
Bitcomet works fine here under Vista.... They updated it a month or 2 ago,
it would lock up Vista before then when you would stop a transfer but, after
the update, works perfect here...
Just like with XP you will have to purchase Nero 7 if you want it to work. I
had to do that. Also, even the Nero 7's available in the stores don't support
Vista. You have to download the ENTIRE newest version from the Nero website
and add your install code.
I use BitComet. You need to download the most recent version and make sure
the ports in the firewall are open.