Thank you Graham.
There was, it turns out no other OLMAPI23.dll file, but I did have some more odd behaviour from Office (eg. There was a configuration process to go through whenever I opened Word). As a result I opted to unistall all MS Office related programs, and re-install my Office 2007 - which I have done. I was impressed by the way Outlook automaticallyfound my email accounts, and had all my folders of emails waiting for me.
How does it know to do that? Amazing.
Anyway, I should think that the problem(s) is now resolved, at least until the next one shows up . . .