Taskbar bug (help needed)

Running back to a decade's old OS that was never meant for consumer use is certainly not the solution. Something is likely corrupted in the OS, most likely from another app, or you have something running in the background that's causing app freezes or causes them to not respond.

I don't see it listed, but have you tried running the system file checker, running a repair install, or even considered a clean install? A clean install would be the final step, but in two hours time or so, you'd have your system back up and running clean.