I've just been through the following problem. Keil support fixed this for me, but I thought the info could be useful on this forum.
Problem: My uVision 4 installation had failed. When I tried to start uVision4, the splash screen would show but do nothing else and the Uv4.exe process was taking 80-90% of my CPU.
If I forced the application to close via Windows Task Manager then I got the message that "SecSplashWndParent" cannot be closed.
I tried a number of ways to remedy this (various combinations of uninstall/re-install).
The route that worked was: 1) Uninstall 2) Reboot 3) Re-install 4) Before you try to start uVision delete the following registry keys and sub-keys: HKEY_CURRENT_USER\Software\Keil\µVision4 5) uVision4 should then start as normal.
DISCLAIMER: I suspect that most people who read this forum are competent enough to edit the registry. That said, don't blame me if this change breaks your machine.
Regards,
SteveO.