Unable Select Multiple Items in Seach and Link

This is an odd frustration that I found the other day which has a tendency to get you looking into all sorts of problems before you find the cause...

Version : ITSM 504 SP1 Patch 3

Symptoms: Create new Incident, Attempt to link multiple Inventory items by holding Shift Key and Clicking on Start and End of List.

Error: OK Button is not enabled.
Error occurs for ever search and link button on all relationships.

Workaround: Must Click on one record whilst holding CTRL key before OK button is enabled.