Marketing Documents - Long time to Update

Hello experts,

     I am having difficulties updating or even changing values and tabbing away from Header UDFs in Marketing documents with open lines.

It looks like the system goes through all the lines or something, as it takes a very long time (depending on the number of open lines in the present document) to move on.

I have checked UDFs and FMS's and I cannot find anything out of the ordinary. It is really becoming a problem for documents with 100 lines or more, where it can take up to half an hour to update!

     Any ideas?

Thanks in Advance

Alex