I haven't encountered a problem with computeWithForm directly, I've used it quite a bit. Do you have the datasource more than once on the page? A save could be saving all instances of the datasource and computeWithForm causing a conflict.

As far as I know only one (I am an XPages newbie).  I have one datasource defined for the xpage.  If I remove the compute withform then the rep and save conflict does not occur.

 

I don't seem to have any problem with computeWtihForm if I only have one datasource on the page. But I do if I have more than one.

 

Have you got any other dominoDocument datasources at all on the page? Remember that if you have multiple dominoDocument datasources but don't use ignoreRequestParams, they will all use the UNID in the URL. If I have multiple datasources without ignoreRequestParams, I am seeing the replication/save conflicts.