I have a Visualforce page containing a commandButton that takes a user selected option from one selectList to another.

<apex:commandButton value=">>" id="to_select_add" action="{!AddToContact}"/>

It's a button users may click on more than a few times in quick succession to make their selection. Yesterday an intermittant problem occurred where all data was lost on the form after clicking the button. After debugging it transpired that each time the bug occurred a debug log with the line:

Log Element thePage called method {!checkManageability} returned type PageReference: none

was generated and the subsequent debug log showed that the constructor was called on the visualforce page controller. The instance of the apex controller appears to have been lost and a new instance created.

Yesterday it happened regularly. I have tried to replicate this problem today and only managed to see it happen once after many attempts!?

Can anyone, preferably Salesforce, shed any light on this behaviour. It's worrying and annoying as there seems to be no information to go on and therefore no possiblilty of getting a handle on this issue.

Please respond if you have experienced a similiar issue.

Thanks