Windows 7: Suddenly can't pin a program to taskbar anymore

This started a week or so ago. I had a program pinned to the task bar, but suddenly it was behaving strangely. When I ran one or more instances of the program, they would group together, but not group with the pinned icon. I could move them separately. Just now, in a attempt to fix this, I unpinned the program, and tried to re-pin it, but that option is gone! Dragging the .exe file to the task bar also gives me the 'not allowed' mouse cursor. Pinning any other program and pinning this program to the start menu is still possible.

Before you ask, I've tried the shortcut arrow fix, but I already have, and always had, the IsShortcut key in the registry.



I haven't installed or uninstalled any programs in the mean time (except for updates), and a reboot didn't work either.

Could you by any chance post a screenshot of the of the problem?

What is the program?

In the case of 32/64 versions, if you pin the 32bit version (of IE, for example) to the taskbar, then run the 64bit version, they will have separate icons on the taskbar.

The problem solved itself. The only thing I did was lock the computer and unlock it this morning, and the program (which was still running) was mysteriously pinned to the task bar and gave me the option to unpin. I unpinned it and again I couldn't pin it. I minimized then maximized the program and I can now pin/unpin it freely.