[Zope] links stopped working

[garry saddington]

I have just noticed something peculiar with my Zope application. All relative 
links have stopped working properly and are now referring to the directory 
above, and therefore failing to find the correct page.
eg.
/folder1/folder2/folder3/dtmlmethod

if i use the relative link "dtmlmethod" in folder3 i get the following error 
message:

cannot find /folder1/folder2/dtmlmethod

Has anyone seen this before? I can correct it by using absolute references but 
I have many such links and they should work as they have been doing.
regards
garry