Further info on problem:
Thank you for your answer but I do not think it 
diagnoses the problem.
What happens is that the normal address "C:/My 
Websites/...." changes to "http://....." when clicking 
on a link. The browser then keeps on wanting to 
connect even on pages that did work beforehand. If I 
load the original index file the address changes back 
to "C:/My Websites/..." and most of the time I can 
then immediately go to the link that gave the original 
problem and load from the mirror without any problems 
the address staying on "C:/My Websites/..."