I managed to get it working after a little fiddling around.
Editing the general.ini file in its default location didn’t seem to have any effect.
On my desktop PC I’d previously moved the default location of the Database folder, so as a test I also moved the Database from its default location on my laptop to:
C:\Documents and Settings\[profile name]\My Documents
…and it sprang into life and started to work placing the characters *0# at the start of each SMS message.
Strange but it's now working perfectly on my laptop also.
Thank you for all your help
Best wishes