|In my case, this issue with the persistent "Open With" box popping up was caused by a virus called GFL.exe. There are other similar viruses which cause the same problem, namely the inability to access a browser and various other websites, including the inability to run regedit. ( I am currently using Vista).|
My solution was to open the Windows Task Manager, and from the Applications tab, click File, then click New Task Run...then in the Open: box type in your favourite anti-virus program, enter and run it. The "Open With" pop-up box did not appear this time.
I typed in Malwarebytes.org, a FREE anti-virus/anti-spyware program that requires no registration. I ran the quick scan feature and it found the GFL.exe virus and allowed me to delete it. Once this was done, I restarted the computer and everything was back to normal.
Hope this works for you.