Some taskbar icons wont maximize

Hello everyone first post so be gentle
I have an issue with certain icons on my task bar not maximising this problem has just started and its on a brand new PC,the icons were maximising but all of a sudden my media player icon and my computer icon stopped maximising.
I have tried system restore and I have done a registry clean but to no avail.
I think its something really silly but its got me beat just now
Here is a screen shot of what happens when I right click over the problem icon.

I must add that on my screen I can not see the enlarged video shot on the right hand side of the screen capture shot that I have included

I have found a way to get url link icons to always maximise.
First make sure that your Internet Explorer always maximises by right clicking the icon>properties>run and making sure it says Maximised.
Then go to Control Panel>Default Programs>Associate a file type or Protocol with a specific program, scroll down to .url and it should have Current Default as Internet Browser. Click on the icon to the left or .url>click Browse and choose Internet Explorer. Then in the 'Open with' window, click Internet Explorer and OK
Your URL link will now open maximised like Internet Explorer but you will loose the ability to change the icon to one you like rather than the IE icon. If you want to have the ability to choose an icon repeat the above but now in 'Open with', 'Recommended programmes' click Internet Browser and check the 'Always use this program....'.

Your url link will now continue to open maximised and also in properties you will have the option to change the icon.

PS Don't ask me why this works but on my system it does for all my url links.