Vista - Anyone else having problems? With application "windows" not openin

I seem to have a problem where at times I may click on for example, IE, WMP,
or even a buddy in YIM and the window for that particular application will
not open. I may try a number of times and it will still not open any more
programmes or applications, or windows of existing running programmes (extra
tabs on IE, windows on MSN)

What is the problem? Is this a common Vista bug?

This is not any "common bug" that I'm aware of. However, the specific symptoms you mentions can be caused by a great many things, not the least of which is perhaps a bad mouse. Try using a different mouse to see if that helps.

How much memory does your computer have? Insufficient memory could also result in these symptoms you describe.

Since you mentioned Yahoo Instant Messenger, I'm inclined to think that you have perhaps developed a malware infection.

I cannot be any more specific without further details from you...