Programs and Features will not open

I can only think of a couple of reasons (this is a basic feature):
1. The userid you are using does have admin permissions
2. You have some sort of virus, malware or basic system corruption.
... Thinkpads_User

Does
control.exe appwiz.cpl
also not work?
(Type it from a command prompt)

If no good, I've read of someone doing the following to fix it (also from a command prompt):

regsvr32 appwiz.cpl
regsvr32 mshtml.dll

Thinkpads -  User is setup as administrator with all the usual permissions... and no malware, viruses or adware - system is as clean as a whistle! :-)

cantoris - The "control.exe appwiz.cp"l command causes just the outline of a window to appear for about half a second - then it disappeared.  

The "regsvr32 appwiz.cpl" command returns this error:
The module "appwiz.cpl" may not be compatible with the version of Windows that you are running.  Check if the module is compatible with an x86 (32-bit) or x64 (64-bit) version of regsvr32.exe.  This may be onto something as this Windows vista started out as version Home Premium and was upgraded to Vista Business (32-bit).

The "regsvr32 mshtml.dll" command returns this error:
The module "mshtml.dll" was loaded but the entry-point DllRegistryServer was not found.  Make sure that "mshtml.dll" is a valid DLL or OCX file and then try again.

Thanks for your input everybody!

Oh - one more thing....  Vista SP1 will not load.   Error says - "an unknown error occurred"

This sounds a rather more fundamental error then.
Have you tried
SFC  /SCANNOW

I would say you either have some significant virus/malware or software corruption as suggested in my first post, or possibly have a hardware problem (memory or hard drive).

If you do hardware tests and they work out OK, then you probably need to save your data, re-format and re-image your system. ... Thinkpads_User