MY PC advises that there is an attempt to change a registry value to
incorporate a value crodbc.exe.  However I can find no reference to
such a program on Google and fear it may be spyware.  Can you help
identify what this program is please?

you should be aware that viruses have a "morph" feature, where they
change many aspects of themselves to different degrees.

spyware changes daily, as does malware.

there are dll's that can run on a system and create a "ghost" exe that
does not exist in the task manager.

the best deal here is run a couple of spyware removers and check the system.
make sure you have a firewall running which will advise you if a
program is trying to access the web. also, remove everything from your
startup (type msconfig.exe in the run area).

you will not find a reference to many erroneous exe's. what matters
is, did you ask this program to do this, and if you did not, something
is running which is trying to change you system and you should remove
it.

good luck