Macbook Pro Weird OSX problems

[lisharts]

A few weeks back when exiting a game I found my desktop image disappeared and was replaced with a blue background. I right-clicked and changed background picture back to what it was and it seemed to fix it. Hasn't happened since. However whenever I get a prompt requiring my password (to authorize something) the box and it's buttons appear to be empty and the little wheel just spins and spins. So I can't enter my password.

Any ideas what could be causing this and how I can fix it?

Thanks.

 

[spinnerlys]

What exact/specific Mac OS X version do you run on what specific/exact Mac?

 

[lisharts]

What exact/specific Mac OS X version do you run on what specific/exact Mac?

Sorry should have said that to begin with, it's a brand new Macbook Pro (i7) 15". It was a replacement as my first had faulty hardware.

It's running Snow Leopard 10.6.4.

I've just run repair disk and it repaired loads of thing to do with airport but the last two messages were:

Warning: SUIS file "system/libary/priateframework/admin.frame...a/resources/readconfig" has been modified and will not be repaired. Then the same but ending in writeconfig

 

[lisharts]

Just for some backstory as well the reason I noticed this is I forgot my login for ichat. After a quick google I saw it was possible to look this up in keychain access. So I open that up and when I right-click on ichat and try to copy the password to clipboard the box (which I presume is asking for my admin password) pops up. All 3 buttons are blank, as is the rest of the box. The wheel just spins. Eventually I can close it, seems very odd though. Like I say this is relatively new and I don't have my applications installed. So confused as to what might be upsetting it.

Also can post a pic of this if it will be helpful.

attached now