Vista - "X is not a valid Win32 application" Error on EVERY executable

When I try to execute ANY ( yes, any ) executable ( *.exe/*.msi etc) file, I
receive the error msg "is not a valid Win32 application". I am now at the
point I can not add or update ANY software whatsoever due to this error
coming up for any executable.
Im running Vista Home Basic, I thought I was a power-user until this one,
and my goal is to either A) Find out the problem and a fix for it. -OR- B) If
someone could explain what a valid Win32 app is- I may be able to figure it
out from there. The online services have been NO help. MS help does not say
why this error happens other than corrupted files ( but eg: if I compile a
functional C++ script to an exe, that too is "not valid" ). So ANY help or
IDEAS on a fix for this, or just what it MEANS would help.
Ironically, I work in tech support, and I know my way around windows on an
intermediate / trained level. This is making my laptop a paperweight, any
ideas appreciated! Thank you so much!

Welcome to the forums!

Is there a specific error code generated when this happens, like error # 0008x000ff or something? If it generates an error code, it will help me find out what is happening and direct me to find a solution for you quicker.

I've been doing some more reading about this error message (without the error code). If this is happening on every file you try to run, then it makes me think that your system files have been corrupted some how.

First I'd try a system restore to a point before this started happening and see if that resolves it (if you can get it to run).

Next, booting off of the Vista DVD I'd do a system repair. This should hopefully fix this issue.

Please let us know if this works for you.