This is a bit of a public service message to anyone who experiences issue with opening the Logitech Profiler -- mine suddenly would not launch despite reinstalls etc...but I found this solution on the net which works great: If you are running Windows 7 64 bit, I recommend you do the following. go to the following directory in your computer (you will have to enable hidden files view). C:\Users\REPLACE WITH YOUR USERNAmE\AppData\Local\Logitech\Gaming Software In the folder above I found several xml files. I moved them to a temporary folder (I recomend you do the same). Then I had no problem starting the program again. I then imported backups of my profiles (shame on you if you don't make backups) and it seems to be working fine now. I am not sure if this will solve things for a long time or not, but it appears to have fixed the issue for now. I am assuming that one of the xml files became corrupt through a windows glitch of some sort.