This is what happened. I was using MIRC fine yesterday. Leaving the computer and MIRC on, i went to sleep. I woke up today and realised i could not alt-tab between MIRC and any other windows, even though i havent done anything with the comp since yesterday.
What happens when i try to alt-tab(or just click on the other windows in the taskbar), is that window i try to switch to will maximise. However the windows will not switch from MIRC to the other window i selected. Heres a pic :

As you can see i have attempted to alt-tab to my firefox window. However MIRC is still the "Active" window, even though it is "unselected"(white window border instead of gray).
I have tried rebooting, as well as doing re-installs, with no luck. This just came out of nowhere and i didnt do anything AT ALL, it just...HAPPENED.
Any ideas?