Very strange issue here - I simply cannot open the IIS 7 manager by choosing it directly.
My OS is Windows 7, and as such, I can see it's opened on the Start Menu aswell as a preview of the window itself when I hover over it. I cannot however, see the actual window itself. I can click it on the task bar (it does 'start'), and it doesn't report any errors - it's as though the window will not maximise...
Even more strangely, I can open the IIS manager by starting the MMC and adding the IIS Manager snap in - which works fine...
I found a new solution. First, when we get this error IIS Manager couldn't appear. Go to IIS Manager and right click to go Properties. On the shortcut section you can see Run line. Change this value to Maximized and click Apply or OK. Open IIS Manager again.
After just experiencing this problem myself the solution I found in the end was to open task-manager shut down explorer.exe in the Processes tab, maximize IIS in the Applications tab and then run explorer.exe as a new task.
I am aware of the age of this thread however I just had this happen to me on a machine running Server 2008 R2 and this post was the only related article I could find so I'm hoping my contribution will help a future user in need.
If right clicking on the shortcut does not present you with the Maximize option then wait until a window hovers over the shortcut (assuming it's pinned to your task bar and your mouse is on the shortcut) then right click the window. Maximize worked for me. Glad I didn't do a reset or install/uninstall