If your computer brings up a window every time you click on a program’s icon asking what you want to open it with, there’s a not-so-obvious way out.
Ve hev vays to get a command prompt when executable files won’t run normally. And from there, you can run anything you want, old school DOS-style.
First, hit ctrl-alt-delete and select Start Task Manager. Click on the File menu, then hold down the ctrl key and click New Task (Run). Windows will give you a command prompt.
From the command prompt, type %systemroot%\system32\restore\rstrui.exe and hit enter. (Sometimes you can get by with just typing rstrui.exe and hitting enter.) System Restore will launch.
Now, select Restore my Computer from an Earlier Time and click Next. Select a date before your computer started having the problem. Click Next. On the confirmation page, click Next again. After the computer restores itself to its earlier state, it will restart. Log back in and your system should behave much closer to normal now.
You can find more information on System Restore on Microsoft’s site.