I have a problem with inconsistent 1733 Errors ('Class Deifnition X Not Found.')

I've made a couple of posts on U.T. about this problem, but now I've positively
identified the cause of my problem as the ALIAS's in SET('CLASSLIB') being
"altered" whilst the application is running.

There is "nothing" in the application which alters the value of SET('CLASSLIB'),
except for a single section of code which is only executed at the application's
startup and loads all the class libraries assigning them ALIAS's that are equal to
the stem of the VCX filename, i.e.

C:\Path\MyClass.VCX ALIAS MyClass

What I'd like to know (besides a resolution), is whether anyone else has experienced,
or even heard about this problem before, i.e. is it a known bug in VFP6?

Any input appreciated,

Regards,

- Aaron.