Thanks for the advice.
But it did not help. :(
I still get the same thing happening.
I have attached a screenshot of what happens to my admin panel after I installed something using Magento Connect Manager.
However… If I click back in my browser (Firefox) and uninstall the app/whatever I just installed… my Admin panel comes back…
So I can get it back BUT it means that I cannot do upgrades to existing installations and I cannot get anything new from Magento connect.
So if there’s a developer out there who’s had similar happen to him or her.... Please help…
Click thumbnail to see full-size image